Two students pair up. The first one is given 10$. He has to give a number of dollars to the second student; if the second student accepts, they both keep what the first student allocated each of them; if the second student refuses, they get nothing.

Economic theory would suggest that as long as the second student gets one dollar, he is better off, and will accept any split. Practice, again, shows that students were willing to forego their dollars if they felt the split was too unfair.

Can't find the references right now, but it's quite famous.

In the long run, we're all dead. John Maynard Keynes