Can sperm swim from the outside of the vagina (like say on the inner labia) into vagina? how likely is this gonna cause pregnancy? i always thought you had to ejaculate inside the vagina.

Preg. very unlikely: In real life, pregnancy usually does not happen that way. There generally is not enough semen to run down a thigh, over the vulva, an into the vagina. Ejaculation usually has to happen into the vagina in order to create a new baby. That being said, life can surprise you sometimes. So, couples having sex should always be ready for that rare surprise baby.