If a guy rubs his penis against a girl's vagina and the girl just finished her period and washes herself there right after the guy rubs against her is there a risk of pregnancy?

yes and oh yea

Look man it depends on how much semen you ejaculate and how close the "load" lands inside of her... if you squirt on her belly button- good; if you squirt inside of her vagina- baby. Remember condoms are safe but using one means you are having sex with a rubber sack...sorry