1) An adjective describing a state of superlative satisfaction or happiness, equal to what one would feel during a sex act with TV's Gidget.

The act of locking your young lady in a Full Nelson wrestling hold whilst ploughing her from behind.

In a precarious situation; see "hairy"
My friend in college was dating (may still be) a woman with very hairy eye-brows. I nick-named her "Brows." One early morning, a friend asked where my friend who was dating "Brows" was. He was indeed in bed with her, doing the nasty probably, although we always gave him a hard time about it. I thus simply answered, "Balls-deep in Groucho." From then on it became synonomous with being in a "hairy, tight, or precarious spot"

When a person or persons lick a mans testicals so hard that the balls fill their mouth.

A phrase that breaks any deceiving between friends.
If asked if one is being balls deep honest, they absolutely, 100% of the time, undoubtedly must reply with the complete truth.

During any sporting event, when someone has been throughly fucked.
When everone agrees that they were completely embarrassed.

When the ass is so fucking stretched that it goes ALL the way in and gets a bit of the balls too, maybe the balls of this dick is comnected to the dick in such a way to where it's like connected to the cock and some of the ball sack gets sucked into the ass. Because like, if you are goin in, Boom, Dick. Balls. Allll the way in. What's left to go in but the balls, the closest dangly thing on your... body? Cuz you're not gonna get anymore! Everything else is too BIG on the body, that's the ONLY thing left, at some point the ballsack is just gonna go oowwowoOAOAAHOOHHH