When Keine Kamishirasawa from the Touhou games transforms on the full moon, goes crazy, and rapes you in the ass with her horns.

The term's association with said ass-raping comes from a butchered English-to-Japanese machine translation where "caved!!!!" became "screwed!!!!". Used by mostly Japanese-speaking Touhou fans, but a few English-speakers have also adopted the term.

v. To give up to all opposition, usually in an argument.

The psychological need of someone to close down the window shutters, dim the lights, turn off the phone, eat junk food, surf on the internet, watch TV, listen to music and use drugs, remaining in this condition for few hours, days or weeks, into her/his flat, denying to go out or to meet anybody, like she/he is hiding into her/his own cave. Strongly connected to Minor or Major Depression and Agoraphobia.

The deepest trench of the arm pit, or under tit. In other words, when you place your arm in a certain position and flex your pectoral region, the cave will form.

The ongoing act of giving in to something.

Means "old news."

Originated on Lambgoat.com

Caved on, caving on
To Cave on is commonly used meaning having a repulsive gesture and figure against being fingered(by a loved one or anyone else in particular).