I agree with the others -- it would strike me as odd for college girls/women to refer to staying at each others' houses as a sleepover. Even if they're at home with their parents, I think they'd be more likely to think of it as a visit / hanging out and they just happened to plan for one of the friends to stay over. I mean, think how adults do it: "Hey, we could go see the movie and then you can crash at my place after."
What they do together depends on their interests. Movies, video games, ordering food -- all believable. Codes to me that they're introverts, just so you know. The other posters' suggestions are also great, and strike me as a little more likely, unless your young women are supposed to be off the center of the bell curve. Other things college-aged friends might do together: go out and do any of the following activities, depending on their interests -- dancing, clubbing, ice skating, relaxing on the beach, bowling, hiking, yoga, sushi, other eating out, going to the movies, setting off model rockets, shopping, seeing roller derby, seeing a sports game, seeing a play, playing paintball, driving to see Christmas lights (if it's that time of year), going to see local tourist attractions, going to an amusement park, going to a bar, going to a concert or comedy show or poetry slam, going to a parade or other live event, rock climbing, walking around a touristy type of place (like a boardwalk or a particularly beautiful area of town), swimming/boating/fishing in a lake if you're in a rural setting, going to a bookstore if they're readers, going to the spa or to get manicures/pedicures . . . or staying in and do any of the following activities, depending on their interests and how mainstream they are -- movies, TV shows, video games, cooking/baking as a social activity, board games, roleplaying games, working out together, stretching/yoga, doing online quizzes, getting drunk together, deep conversation, building something together (a computer? a robot?), s'mores, lighting things on fire (depending on what kind of girls they are . . .), talking about the boys or girls they like, talking about classes, working on homework together (depending on what kind of girls they are . . .), going for a walk together, stargazing, playing cards, making out if they're queer or curious and are attracted to each other . . . honestly, the possibilities are endless, it really depends on who your young women are and what they *like* to do. I mean, what Pair of Women A do together when hanging out will be vastly different from what Pair of Women B do when hanging out, so I think you need to ask your characters what they like.
College-aged women are basically adults, so just think what
people like to do together and you've got all the possibilities.
