Never leave before the end of the movie

Here is a salutary lesson, related to me by Bob Gibbons. He was at an event in New Zealand when he, and his friends, spotted a game which began 1.e4 e5 2.Nf3 Nf6 3.Nxe5 Nxe4? Now most people know why this is bad, and of course the game continued 4.Qe2 Nf6 5.Nc6+ Be7 6.Nxd8. At this point they had decided they'd seen all that was needed to be seen and wandered off. When the returned to the tournament they saw that the score was down as 0-1 and thought there must have been some sort of mistake. It turns out they had left before the real fun began. Black had continued 6. ... Kxd8 7.d4 Re8 8.Qd1?? when Black ended the game with 8. ... Bb4++ and mate! Apparently those that did stay until the end said that Black behaved like what happened was the most natural thing in the world!