Balls deep is a descriptive term that pertains to the depth of intercourse. It literally means that the penis is so deep in the vagina or anus that the man's scrotum touches the base of the vulva or ass.
More About Balls Deep
Balls deep can be used outside its sexual context. It is heard in everyday conversation and pertains to being deep into a thing or a situation. For instance, a person can be “balls deep” in work. As in all things, balance is necessary, and being “balls deep” may create problems. Sexually, being balls deep can put unnecessary strain on the scrotum. In everything else, it can put a strain on relationships and other passions.
