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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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 


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



A swiftie. Most of you are probably too young to remember them... " $s = \displaystyle\int_a^b \sqrt{1 + [f'(x)]^2}\mathrm{d}x$ ", said Tom at length. 


Tom Lehrer was a Mathematician and this comes through in several of his famous skits. Not precisely a "math joke", but still mathy and pretty darn funny. 


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". 


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." 


A friend made this up recently (I prefer the first half on its own): "No meal is complete without soup. But you have to order it first." Also I like this metajoke, also by a friend (who didn't understand the original): "What's purple and commutes? An abelian eggplant." EDIT: one more, by Elizabeth: "Does this Hausdorff measure make me look fat?" 


What did the forgetful functor do for his stoner friend? He left adjoint as a free object. 


A millionaire is trying to scientifically develop the best racing horse. He asked a biologist, veterinary, trainer, and a mathematician. The biologist gives him an advice about which type of horse to cross with which other type, the veterinary advices on how to feed the horse, and how to keep him healthy, the trainer explains how to physically train the horse. The mathematician does not reply. After a few weeks the millionaire meets the mathematician and it looks that the mathematician did not sleep much in recent days. Do you have a solution for me, ask the millionaire? It is a difficult problem, answers the mathematician, but I think I have a satisfactory solution to the case of spherical horses. 


I excuse my english if you spot some flaws...., since this is my first post here I thought it would be nice to share some neat jokes. 1) A mathematician, a physicist and an engineer were out in the countryside when they met a farmer trying to build a fence. They introduced themselves and the farmer asked them if they could help him shape the fence so he would get as much space as possible within it. The engineer stepped forward and said, that it would be best for the farmer to make the fence square, that would be easiest. The physicist then said that it would be better to make it as a circle, because then he would get as much space as possible. The mathematician laughed and said that you can get a lot more space then that! He took some pieces of fence and rolled it around himself, then he defined himself outside the fence! 2) Infinitely many mathematicians walked into a bar, the first one asked for one beer, the next one asked for half a beer, the third one asked for a quarter of a beer and the fourth one asked for one eight of a beer, then the bartender said :"screw this" and filled two glasses of beer! 3) An engineer was working on a problem when suddenly his trash bin caught fire. He immediately grabbed the fire extinguisher and put out the fire. In the next room a physicist was also working on a problem when his trash caught fire, he thought, fire extinguisher block oxygen from the fire, ergo fire is put out. So he grabs the fire extinguisher and puts out the fire. In the third room there was a mathematician working on a problem, his trash bin also caught fire so he looked at and thought, problem has a solution, and continued working! 


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



In a math party, all were having a good time. y was the dj, everybody was Riemmanly drunk. Then, when the x saw e^x on a corner crying, he asked:  Hey e^x, why don't you integrate ?  Because I keep always the same!!! 


Posterior Analysis: when a statistician looks at the rear end of a member of the appropriate sex. 


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." 


After introducing general topological spaces, the professor began to introduce the notion of convergence without a metric. He turned around and said, "I have no balls." A hit for months. 


Mathematician1: So why did you become a mathematician? Mathematician2: I don't like working with numbers. 


a pure and applied mathematician were sitting in a bar, when they spotted a hot chick 2 meters away. However, this was a weird place where they could take one 1 meter step and each consecutive would have to be half of the length of the previous one. The pure mathematician was sad because he knew he could never get to the girl. The applied one was happy because he knew that for all practical purposes he can get close enough. 


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


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


Fesenko's math joke collection, selected from the Cherkaev collection. 


The answer to the question posed in the title "Do Good Math Jokes Exist" is yes and is easily found on google. 


Q: What did the threefold blown up at two points say while waiting in a long line for a restroom? A: I have to pee too. 


Here is a joke I invented (based on a famous one) and had mixed reaction. A young mathematician comes to present to a famous mathematician his conjecture and ideas. "You are absolutely wrong," the famous mathematician dismissed the young one. Next enters another young mathematician and presents precisely the opposite conjecture. "You are absolutely wrong" replies the famous mathematician. The famous mathematician's wife interferes. "How could you tell both of them that they are wrong," she sais. "They have made completely opposite claims, one of them must be right!" "You are also wrong," replied the famous mathematician. 


I enjoy this page of Milne's Tips for Authors. I also find the book Mathematics Made Difficult by Linderholm to be hilarious. I'm not going to search for favorites, but I find the first 2 exercises amusing: "1. Show that a finite subset of an arbitrary set E in a ring suffices to generate the ideal generated by E if, and only if, the ring is Noetherian. *2. Show that 17 x 17 = 289. Generalize this result." 


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. 


I once adlibbed this one. (Alas, it is a late entrant.) Q: Why is it important to study Verma modules of Lie algebras? A: The most widely used modules of Lie algebras and Lie groups are finitedimensional irreducible representations, the Weyl modules. Of course, you should learn them first when you study representation theory. But they are only the tip of the iceberg. 


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 $0$. 


Less of a joke than an observation, but... I've always found it appropriate that online identity thieves are in the business of stealing ones and zeroes. 


Q: What's purple and commutes? A: A dead baby in a suitcase. Q: What's purple and commutes and has a certain number of followers? A: A dead baby Jesus in a suitcase. 


Q: What's purple and commutes? A: An abelian grape! 

