Missouri Court of Appeals November 6, 2018, WD 80736 (State v. Barbee)

But one thing I want you guys to understand is the State is not saying that he had sexual intercourse like you and I think of where it's a complete act, and I am not going to get gross, but what I want to say is that under the law, sexual intercourse is penetration, however slight, of the female sex organ by the male sex organ.