What about the pigeonhole principle?

EDIT: This small answer is being vandalized by spammers twice a day. I learnt on meta that if an answer is at least 400 characters long, then massive modifications are not authorized unless the user has some reputation. It is with reluctance that I am therefore forced to annoy all mathOverflow companions with this non-mathematical modification. Fifteen more chars, and it'll be OK... Now it is, I am even over by sixty seven!

What about the pigeonhole principle?

What about the pigeonhole principle?

What about the pigeonhole principle?

EDIT: This small answer is being vandalized by spammers twice a day. I learnt on meta that if an answer is at least 400 characters long, then massive modifications are not authorized unless the user has some reputation. It is with reluctance that I am therefore forced to annoy all mathOverflow companions with this non-mathematical modification. Fifteen more chars, and it'll be OK... Now it is, I am even over by sixty seven!