They didn't know why these things were funny. Sometimes you laugh because you've got no more room for crying. Sometimes you laugh because table manners on a beach are funny. And sometimes you laugh because you're alive, when you really shouldn't be.
Terry PratchettTiffany knew what the problem was immediately. She'd seen it before, at birthday parties. Her brother was suffering from tragic sweet deprivation. Yes, he was surrounded by sweets. But the moment he took any sweet at all, said his sugar-addled brain, that meant he was not taking all the rest. And there were so many sweets he'd never be able to eat them all. It was too much to cope with. The only solution was to burst into tears.
Terry Pratchett