Definition: when a guy accidently puts his penis in a skanks vagina, however, because she is such a whore and has slept with 80 people, he can not tell that his penis is inside of her. This continues for a few minutes until he realizes from her slutty ape grunts that he is indeed having sex. He immediately pulls out. Thus, "barely having sex."
Note: This may also include the occasional tip of dick rubbing the clit.
Barely Having Sex: "Baby, I only barely had sex with her. Don't worry.