Thanks for using just answer.
Well, One can only get pregnant if a guy ejaculates his sperm while he is inside the girl's vagina. Siting on sperm COULD cause pregnancy if there was a lot of it and you deliberately got it up there very deep. Having said that, sperm only stays alive outside a body for about 4 minutes so depending on how old it was, you COULD. The chances are 1:1,000,000,000 and that's even if you got it up there with your fingers or something.