My girlfriend's snatch is really narrow. In fact even her doctor says she has a tight snatch (well, maybe not in so many words). I can only get like four fingers in there on a good day. What's a good way to stretch it out? I thought about sticking a couple condoms or a small water balloon up in there and then gradually inflating it with an air compressor but I'm afraid it may stretch too much lengthwise and not enough widthwise.

My goal is to get two fists up in there but I gotta start with just one!