Some people like cake, my friends like oreo birthday brownies. I have to admit it's a pretty practical idea as the birthday girl/boy get's an enormous brownie slab with icing and enjoys smugly watching as the ordinary folk of the day consume regular sized (But equally delicious) brownie squares. So everyone shares the Birthday deliciousness, but a class system stays in place-and on a birthday, it surely should.
Most ask for "happy birthday", sometimes their name, sometimes I add the number. My most...interesting order was definitely the "expelliarmus" brownie; for a girl who'd never seen, read or displayed any interest in Harry Potter but greatly enjoyed my difficulty in researching how to spell the word, and struggling to fit it's 12 letters in writer icing onto an unreasonably restrictive brownie. Really, it was quite a clever trick to force me to make the brownie even bigger.
(Just so you know-brownies also make excellent bake sale pieces and I've even made an apology brownie before to compensate the boy I gave a rash with my notorious Nutella buttercream.)