Alcohol

Unless you're a heavy drinker, alcohol won't cost too much and is guaranteed (in most cases) to give you a good time. Just don't become a raging alcoholic, because though they're fun to hang around with, I doubt it's much fun to be one.

One suggestions is to do everything on this site (or everyting IN sight) while drunk for double the pleasure.

While you're at it, you might even want to play some drinking games.