why do girls all go to the washroom together?

Lesbian experimentation.... I wish. There's tons of reasons why women go to the bathroom together. The main one being that they want someone to talk to, or wish to discuss something private with the other girl. Having another person with you also comes in handy when you manage to get a stall with a door that never closes. There's also exchanging makeup and other feminine products. But as I said before, they do it for the conversation. There's no such thing as a 'quiet' women's restroom...unless it's empty.

Usually when I am out with my best friend we go to the bathroom together to check each other and make sure we look okay, and if we are at a club we usually tell each other how horrible the guy dances or how he was a great dancer. Also I feel safer going to the bathroom with someone else just in case anything happens.

We go together to talk about you behind your back. Be afraid.

So they can gossip, re do make up, and sometimes they actually have to use the bathroom. And if you are on a double date, the ladies are talking about you guys.

in my opinion, girls do this because they like checking each other. how they look matters a lot to them. and they also seek opinion and ideas from others. at times, they go there not to satisfy the call of nature but simply to have a look at themselves. i think girls value their appearance very much with which we, guys, should live with that.