If there is sperm on the bed and a girl sits on it can she get pregnant?

If there is semen on a surface and a woman applied her vagina directly to it, and the sperm hasn't been there very long (IE: Hasn't dried out and died), and the surface itself was not porous enough to absorb the semen, then there's a very, very slim chance some sperm would have made it into her vagina. However, it's not likely this resulted in pregnancy.