Making money by doing one-time jobs?

you know you were a kid you would take the bottles down to the recycling or you mowed your neighbor's lawn? i was wondering if there was something like that for older people. like jobs that you could do for a day or for a brief period of time and still get paid. I'm asking because i'm going into university in the fall and i won't have time for a job, but at the same time i could use that little extra money for when you feel like going out for the night and chilling with the guys, go see a movie, etc. etc. i wonder if this idea is a reality, or is it something that left along with my youth.