I've been past four schools today and at all of them the kids are wearing their pyjamas to school... doing something funny for money! I think not.
Plus I was talking to a friend who said she'd had to go and buy new pyjamas for the occasion because her sons are all a bit small and while that's fine for at home it's not fine to send them to school in. Extra cost for her and then she had the nightmare of persuading her boy to wear pants under pyjamas... "you don't wear pants AND pyjamas mummy".
It sounds like a nightmare...
What about a gurnathon? A giant jelly contest? Making a funny black and white film. Writing an essay in alphabetti spaghetti. This is just off the top of my admittedly weird head....