[victoriana]

Technically, none of this is allowed by our nationals. However, pretty much everyone does it, at least on my campus. A girl usually asks a guy to be her little bro when they build up a close friendship after a while of hanging out, it's not a spontaneous thing. A guy can ask a girl to be his big sister too. It doesn't really matter. There's also big brothers and little sisters too. It works the same way. Usually they get matching letters that say "ABC Lil sis" or "XYZ Lil Bro" underneath and make each other paddles.