We were talking to friends about their fertility woes and the awkwardness of the husband giving a "sample" at the doctor's office.
Friend J: So, I have to ask. Are you allowed to use lube or anything?
Husband: Nope. Nothing. Not even water.
Friend J: What about spit?
Wife: No. Saliva kills sperm.
Me: Ohhh... So that's why you don't get pregnant from blow jobs!