A:doesn't know the answer to
B:doesn't want to answer for the purpose of keeping the asker in the dark about information
C:wants to give a fake answer to for comedic purposes
teacher- "What's the exact population of Uzbekistan?"
student- "on top of the fridge
(example for b)
kid- "hey yo ma what am i gettin fo christmas?"
ma-"on top of the fridge"
(example for c)
Guy 1- "Hey dude when's the band meetin up to play the gig at the coffee shop?"
Guy2- "On top of the fridge."