I started work as a cinema usher at 15. Cinema usher encompasses a lot of things: fast food cashier, door attendant, janitor, ticket cashier, and my personal favourite: lifting a 20kg can of solidified oil up a lfight of stairs and then down a different flight of stairs. The variety means that you could have a few shifts a week that are quite different in nature. It's not particularly stressful, unless you're working on the night of a LOTR or HP movie coming out (and probably Transformers or something too).
Over the years I've come to the conclusion that the features of the job (free movies, variety after the first few months, easy work during school-period daylight hours) attract a lot
of slackers. I kept the job because the manager allowed me to work only during the school holidays (letting me concentrate on schoolwork otherwise) as well as the job's extremely relaxed attitude towards time off (as long as you let someone know a day before the roster was done, you were good to go).
It's not that different from fast food, from what I understand (free meals is on par with free movies, though far less healthy), though fast food is probably a little busier.
I obviously don't work there any more, but I regard it as a pretty essential part of my professional development. It built a lot of confidence, as well as teaching me how to read people (so
much more useful than you think).