Nearly unanswerable, since the one who tries to change it usually drops it, and the others call for a planning session.
or
I thought, "He's trying to pull a fast one".
or
A cow walking backwards
or
A car
or
Fifty — one to screw in the bulb and 49 to guard him/her.
or
100: One to do it and ninety-nine to say "I could've done that."
or
They keep dropping their trunks.
or