1) When you go all the way in, all the way up to your balls.

Can also mean

2) in a lot of trouble/peril , in a lot of danger.
She likes when he goes BMFD: Balls mutha fucking deep nside her and she feels it poke her back.

The other day i got caught in a street brawl and was Balls mutha fucking deep right in the middle of it!
by BRICKESE February 17, 2013
Get a BMFD: Balls Mutha Fucking Deep mug for your cousin Günter.
Balls deep means when ur so deep into the pussy that ur balls are in it.
U walk into ur room and u brother is balls deep into ur sister
by Smdlilbich June 30, 2019
Get a Balls deep mug for your friend Günter.
A group of gay boys and one vagina that try and manage fantasy football teams. They tend to whine a lot. All 11 gay boys work for really bad companies. The commissioner is about as funny as Jay Leno, but tries hard to make the other gay boys giggle with jokes.
Everyone wants to play Hubba in the Balls Deep Fantasy League
by BallsDeepSkeet November 15, 2011
Get a Balls Deep Fantasy League mug for your boyfriend Abdul.
when you're fucking a female with a smelly vagina
Ex 1:
boy#1 - yo how was it last night with samantha??
boy#2- terrible, i was balls deep in caviar!!

Ex 2:
bob - hey frank, i heard you were with my girl last night.
frank - bro you could have her ... last night i was balls deep in caviar dawg.
by myabut leaks December 13, 2020
Get a balls deep in caviar mug for your dog James.