Bathroom is probably the safest place. You could try getting your roommates’ class schedules and finding a time when you’d have the room to yourself, or you could try to be sneaky and do it quietly at night after they’ve gone to bed. Both of those options are risky though, which may or may not add to the fun. I also suspect this is a problem your roommates are also experiencing, so coming up with a system (a text in a group chat asking for privacy, a sock on the doorknobs, etc) to say you need some alone time could also help.