First of all, definitely get a job. Easier said than done, but it will eat up a lot of time, and you'll have money to actually go do stuff. Then:
Get a dog!
Play video games
Get a gym membership and start lifting (beach season's coming up
)
Go to the movies with your GF
Cook with your GF
Work on your car
For some reason I really can't think of what I do in my free time... lol I think a lot of it is just chilling at home either alone or with my gf... during the week I'm just busy with school and the gym the whole time, I guess...