When someone unwelcomingly proceeds to force (shove) their strongest muscle in the body (tongue) into your mouth while you desperately try to pull away
For example tongue rape was when Stephanie shoved her tongue into my mouth, when i didnot want to make out with her. It was disgusting.
Tongue Lolling is used to describe when a girl in a hentai is fucked silly to the point her eyes roll up and her tongue hangs out like a dog. It's pretty common in hentai to see a girl lolling her tongue out as some guyfucks her brains out.