How old is too old for Halloween?

When I move into a house one day (apartment), I would make sure to give teens candy since I'd view them all as no-goodniks out to egg/tp the house otherwise.

I stopped fairly early at 6th grade or so (10), since I never really liked the idea of trick or treating for some reason. I wouldn't see a problem with anyone in elementary school trick or treating, quite commonplace. I can see people in high school having fun still and even then only in groups, although I wouldn't be exactly down with that idea. I can imagine the outgoing uni students going in a group. If you're 30 or whatever, then you better be with a kid related to you, or you might garner some cock-eyed looks.

Jam it back in, in the dark.