After suffering a knife wound to the stomach while performing fellatio, a teenager in Lesotho became pregnant in 1988 despite being born without a vagina.
Doctors in Lesotho were puzzled when they discovered that a 15 year old patient going into labor did not have a vagina. The girl suffered from a rare birth defect called Mullerian agenesis. They found out that she conceived her child when a jealous ex stabbed her after performing fellatio on her new boyfriend. Apparently, she got stabbed while on an empty stomach, so she did not have enough gastric acids to kill all the sperm, and the stab wounds opened up a path to her uterus, where she got impregnated.
Sperm can last a long time, so be careful.