It is not scientifically impossible. Back in the 80’s they prived if you ejaculated on the thigh near the vagina or on the outer vaginal area some sperm can make up the vaginal canal to the cervix.
Those boys can swim! Will grow up to be Navy Seals.
I can see that occurring. Lewinskys, fingers, and out of control passionate frenzy means that flying spermatozoa just might end up in places where the two participants never intended it to be.