Where's the Captain?
Not all FOs would do this, but some will. The individual with the most bars should have laid a bad joke to bed quick. My guess is that it was the FO playin' with the FA. Probably had 'em putting out toilet fires the previous flight, and something dumber yet on the one before that. Getting the pax involved was inconsiderate to say the least and proved to the crew who the dumbest really was...THE CAPTAIN (if they were aware); sometimes ya gotta use a little authority! Trying to break up a day of never ending delays with humor is a potentially good thing, but these "pranks" can be taken way too far as in this case.