If you're a college student, most sports on your campus are free for you. And don't stick just to the big football and basketball games. Find the obscure stuff. Amateur jousting? That sounds like a fun sight to witness.
Does this seem like kid stuff? Good. Remember how awesome it was being a kid? Relive some of that with some old games, and find some new ones. There are even board game cafes now, which are cheap and awesome.
No, you're a slave to nostalgia. Seriously, though, kickball is super fun and great exercise. You can even join a league with your friends and make new friends (or enemies if you're ultra competitive).
Remember how much fun you had as a kid for free? You and your group should break out into spontaneous games of The Floor is Lava in public. Sure, people will look at you like you're jackasses, but who cares? You're having fun...for free.