I fell asleep once in the flight engineer's seat while filling out the cruise card. My pen slashed abruptly off to one side as I slumped.
I showed it to the captain, and he said, "Hell, boy, when I was on the panel, I once fell asleep while starting the number 2 engine!"
By the way, when I dozed off it was 4 am local time, and I had been on duty for 10 hours....