Balls deep

[Becky]

(verb) To go into the vagina completely..up to the balls
(adjective) All the way in...balls slapped up against the pussy

[Sarah]

(adj) Specifically, the act of inserting the dick into an orifice up to the hilt, such that the balls rest against the orifice.

(adj) generally, the act of doing any activity hardcore, all out, and as fully as possible.

[Tanya Shivari]

When a male inserts his penis into a partner all the way to the testicles.

[Tina]

to insert your penis into the vagina (or other orafice) until your balls rest against the orafice.

[Sonia]

A pork sword buried to the hilt; the maximum length which it is possible to slip someone; in a sausage and donut situation . The maximum extent to which the sausage can be hidden.

[Becky]

1.deep sexual penetration in which the balls are almost in too.
2.can be used as an expression for something overwhelming, ridiculous, exaggerated, or to refer to a large number of things. Also as an affirmative when answering a question

[Sonia]

To thrust ones penis into a womens vagina to a point where pushing the balls in wouldnt make much
of a difference or.... all worth while.

[Justin Bieber]

Inserting penis far enough into vaginal canal that the testicles push against the outside of the females body.