It happened a couple of years ago in France, at La Ferté-Allais (LFFQ) near Paris, a quite busy GA airport. A few planes were lined up for take-off behind a plane with a female student pilot and her instructor performing an apparently very long checklist. It had already taken 5 to 10 minutes, and the line was extending. (All dialogs below happened, of course, in French.)
TWR:
"F-ABCD, are you ready for departure?"
F-ABCD:
"Not yet, Fox Charlie Delta."
[Several minutes passed.]
Unidentified Voice(presumably an impatient pilot in the line):
"Nails should be dry by now ... ."
TWR:
"Who said that?"
[Dead silence, but after another couple of minutes, Fox Charlie Delta finally called "Ready for departure."]