balls-deep
adv1
Slang, Vulgar With the penis fully immersed in an orifice, more often the anus or vagina than the mouth.
- Near-synonym: bottoming out
- I like to fuck balls-deep. If they can't take it all it's not worth the time.
2
Figuratively, Slang, Vulgar Synonym of neckdeep (“fully immersed or committed (to something)”)
- I'm balls-deep into this essay; there's no turning back.