Places to hangout on a budget?

hey :) im a New Yorker and hang out in manhattan often. sometimes, i dont knw where else to hang out or what else to do. ive been smoking hookah at lounges quite a lot cause im out of ideas. i sometimes go to karaoke bars, but me nor my friends have money all the time. im under 21, by the way, in case someone was going to suggest something like that. when im broke, i often go roam in times square, china town, soho, or st.marks. it gets boring though seeing the same things! any ideas?!