Hooking up means kissing, making out and oral sex. Hooking up means anything BUT sex. Some people use to for just making out, but usually its used for oral sex. Anal sex. Referenced the term anal sex or a description of the act of anal sex.

What does it mean when a girl hangs out with you alone?

When a girl hangs out with you alone, it could mean several things. In other cases, when a girl wants to be around you with no one else around, this could mean that she is interested in pursuing a romantic relationship with you or wants to get to know you better.