It isn't pee.  It is jizz.  I went down on a girl once and she just about put my eye out.  It just kept squirting, just like a guy, but clear instead of milky white.  I was using a dildo on her at the time, so I think it's the clit g-spot combo that makes girls squirt, but I am not positive, because I haven't squirted yet.  I've been told you can learn to squirt.  I hope so, because it's hot!