"Going to the bathroom in groups. Can't they just go alone?"
If girls go to the bathroom, it's often in pairs or groups. To men, this can seem quite foreign. Women get asked about this one all the time, and why it's necessary - and while there might not be a scientific answer, we do have some ideas.
For one, women's lines are almost always way longer than men's lines - so it's nice to have someone to hang out and chat with while you're waiting. Another benefit of going to the bathroom with a friend? Women often carry purses and when bathrooms don't have nice hangers, you definitely don't want to put them on the floor. We've all asked someone to hold our bag while we're in the stall once or twice.
Of course, there's also the reason that men probably fear most - we might want to talk about something in private. Needing to go to the bathroom is an excellent, and seemingly natural, way to pull your friend aside no matter where you are. If something is going on and you want to leave a party, or you just want to chat, you can always ask your friend to come to the bathroom with you and talk to them in private!
Sometimes women also might need a tampon or any other type of feminine product, but might be too embarrassed to ask for it with other people around.
Honestly, we don't see why more guys don't go to the bathroom in groups. It has its benefits!