Have a good joke? Share.
I know this is subjective, but the principle "should be of interest to mathematicians" trumps. (I hope.)
Have a good joke? Share. I know this is subjective, but the principle "should be of interest to mathematicians" trumps. (I hope.) 

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Mike's last joke reminded me of this one: a comathematician is a device for turning cotheorems into ffee. 


Your momma's so fat she's not embeddable in R^3. Oh yeah? Your momma's so fat she contradicts Whitney's theorem. A topologist is someone who doesn't know the difference between his ass and a hole in the ground but does know the difference between his ass and two holes in the ground. I went to visit him while he was lying ill at the hospital. I had come in taxi cab number 14 and remarked that it was a rather dull number. "No" he replied, "it is a very interesting number. It's the smallest number expressible as the product of 7 and 2 in two different ways." 


Here's one I came up with a few years ago that I'm quite proud of.



A British mathematician was giving a talk in Grothendieck's seminar in Paris. He started "Let X be a variety...". This caused some talking among the students sitting in the back, who were asking each other "What's a variety?". J.P. Serre, sitting in the front row, turns around a bit annoyed and says "Integral scheme of finite type over a field". 


Here are a few of my own inventions: Old Macdonald had a form; e_{i} /\ e_{i} = 0 Save the environment: use continuation passing style! What shape of pasta takes the least time to eat? Brachistochroni! You might be a mathematician if you think fog is a composition. The Yoda embedding, contravariant it is. How are Goethe's Faust novels like isomorphisms of sets? Dey're de monic epics. I'm kind of in two minds about this whole Schroedinger's cat thing... qwhine, n. selfrecrimination recursive: (λ damn. damn (damn)) (λ damn. damn (damn)) Coeschatology: the study of the beginning of times. The coend is ming! 


Here's a legend we have at our institute: Prof: "Give an example of a vector space." Student: "V" 


an anecdote about David Hilbert from the wonderful book (for us laymen ;) Prime Obsession:



I like this one: A mathematican walks into a bar accompanied by a dog and a cow. 


I've always thought that "What's the value of a contour integral around Western Europe?" "Zero. All the Poles are in Eastern Europe." was pretty good, although not laughoutloud funny by any means. Another one I personally like is "What's an anagram of BanachTarski?" "BanachTarski BanachTarski." It's not really a "joke," (and whether it's "mathematical" is, I suppose, debatable), but Knuth's article on the complexity of songs is pretty great. 


Don't remember where I saw this, but as a woman in mathematics, it tickles me no end: A poet, a priest, and a mathematician are discussing whether it's better to have a wife or a mistress. The poet argues that it's better to have a mistress because love should be free and spontaneous. The priest argues that it's better to have a wife because love should be sanctified by God. The mathematician says, "I think it's better to have both. That way, when each of them thinks you're with the other, you can do some mathematics." 


My favourite, from Eilenberg's obituary: When someone once asked Professor Eilenberg if he could eat Chinese food with three chopsticks, he answered, "Of course," according to Professor Morgan. The questioner asked, "How are you going to do it?" and Professor Eilenberg replied, "I'll take the three chopsticks, I'll put one of them aside on the table, and I'll use the other two." 


Q: How do you tell an extroverted mathematican from an introverted one? A: An extroverted mathematician stares at your shoes when talking to you. 


Here is the one I heard recently. Professor: What is a root of $f(z)$ of multiplicity $k$? Student: It is a number $a$ such that if you plug it into $f$, you get $0$; if you plug it in again, you again get $0$, and so $k$ times. But if you plug it into $f$ for the $k+1$st time, you do not get $0$. 


I have a few that I've heard and liked. (1) The Mobius strippers always show their backside. (2) Apparently, a quote of Paul Erdos, but it's funny nonetheless : Another roof, another proof. (3) An experimental physicist meets a mathematician in a bar and they start talking. The physicict asks, "What kind of math do you do?" to which the mathematician replies, "Knot theory." The physicist says, "Me neither!" (4) The primary reason Bourbaki stopped writing books was the realization that Lang was one single person. 


jose's post reminds me of one I heard Michael Hutchings tell during an undergraduate calculus lecture:



My favorite oneliner: Why did the mathematician name his dog "Cauchy"? Because he left a residue at every pole. My favorite anecdote: An engineer, a physicist, and a mathematician find themselves in an anecdote, indeed an anecdote quite similar to many that you have no doubt already heard. After some observations and rough calculations the engineer realizes the situation and starts laughing. A few minutes later the physicist understands too and chuckles to himself happily, as he now has enough experimental evidence to publish a paper. This leaves the mathematician somewhat perplexed, as he had observed right away that he was the subject of an anecdote and deduced quite rapidly the presence of humor from similar anecdotes, but considers this anecdote to be too trivial a corollary to be significant, let alone funny. 


"Finite Simple Group (of Order Two)" by the Klein Four a cappella group at Northwestern University (lyrics by Matt Salomone):



There's a mathematician whose nonmathematician friends are constantly ribbing him because his field is just so abstract and seems to have no relevance to the real world. One day, it gets to him, and he resolves to arm himself with some practical applications of research mathematics for the next encounter. He realizes that his own specialty (mathematical logic) is probably too far beyond them to be of any use there, so he goes to the department bulletin board to find an upcoming talk about something practical. Luckily, a talk is scheduled that afternoon on "the theory of gears." "Perfect!" he says. Nothing could be more practical, more downtoearth. Finally, he'll be able to prove to his friends that mathematics is relevant to the real world. That afternoon, he's so excited that he goes to the talk five minutes early and sits in the first row of seats. Then, at the scheduled time, the speaker stands up and begins: "While the theory of gears with real numbers of teeth is well understood...." 


Based on the answers above, no. 


(From the unpublished manuscript "Mathematics in a nutshell":) A coconut is just a nut 


Theorem: There are infinitely many composite numbers. Proof: Suppose there are only finitely many, and multiply them together. 


Q: What is nonorientable and lives in the ocean? A mathematician organizes a raffle in which the prize is an infinite amount of money paid over an infinite amount of time. Of course, with the promise of such a prize, his tickets sell like hot cake. When the winning ticket is drawn, and the jubilant winner comes to claim his prize, the mathematician explains the mode of payment: "1 dollar now, 1/2 dollar next week, 1/3 dollar the week after that..." "The number you have dialed is imaginary. Please, rotate your phone by 90 degrees and try again..." From a former prof.  http://www.math.ualberta.ca/~runde/jokes.html (no longer available) Archived here: http://web.archive.org/web/20121113123413/http://www.math.ualberta.ca/~runde/jokes.html 


"Why did the chicken cross the Mobius band?" The question isn't whether good math jokes exist, but whether they can be classified. The example above works because it plays on ones expectation of the "chicken crossing the road" jokes. Another one in the same vein, known as the shortest math joke: "Let epsilon<0." Another one, which I actually heard in class: "Take a positive integer N. No wait, N is too big; take a positive integer k." Here is a nonexhaustive classification of math jokes:
A joke can belong to more than one classification. For example, the "Dog and cow knot theorists" has both puns and a twist on expectations. By the way, I would exclude jokes which are purely made on stereotypes, like the above joke on extrovert mathematician, because I don't find it funny. I leave with one of my favorite metajokes: "How many members of a certain demographic group does it take to perform a specified task? A finite number: one to perform the task and the remainder to act in a manner stereotypical of the group in question." 


I received today this comment about a paper:



Q: How many mathematicians does it take to change a light bulb? A: One: she gives it to three physicists, thus reducing it to a problem that has already been solved. 


This saying is attributed to someone from Bourbaki in Bourbaki's Art of Memory. 


If I remember correctly someone told me that this really happened: A famous mathematician gave a talk (maybe about mathematical physics), after which an as famous physicist sitting in the first row got up, and loudly declared: "That's all nice, but without mathematics, research in physics would be maybe a week behind the state it is now!" The famous mathematician responded: "Yes, the week god needed to create the world." 





An engineer, a physicist and a mathematician are driving through the high country in Scotland. Atop a hill, they see a black sheep. The engineer says: "All sheep are black!" The physicist says: "No, no, some sheep are black." The mathematician: "At least one sheep is black on at least one side." 


Here are some of my favorites that were invented by friends of mine: Q: What kind of maps should you take with you on car trips? A: Automorphisms. Q: What do you call it when you're trying to prove that a map is injective, but you just can't do it? A: Monic fail. 

