God, this just seems so easy. If you have to ask then maybe you shouldn't be having sex until you have some basic education on it. Ok I have never, NEVER heard of a girl getting knocked up by some cum on her panties. Sperm needs a certin environment to stay alive and if exposed outsde for a while they die. Besides that, unless shes rubbing her panties in her (you never know, whatever gets her off right?) then that really shouldn't be much of a problem.

Reading your post I can't help but think this is a joke topic. If it isn't then you really don't know much about how the reproductive oranges work. Sex + Gril on Peroid = Bad timeing...You want a little kid running around?