So, I can't stand the "why?" Cycle. Drives me crazy, I refuse to be drawn into it with kids.
Eg
Adult: we have to go home
Kid: why?
Adult: because it's 3
Kid: why?
Adult: because that's the time
Etc as the kid finds it amusing that the adult is getting all flustered and annoyed.
My go to is 'I will only answer proper questions, so ask me again properly'. They occasionally ask me one, maybe two follow up questions.
According to a friend, I'm spoiling the kids fun 