Knackers deep

to have sexual intercourse with a female and penetrate her massively allowing for only balls to petrude

"You off out tonight mate?"

"fo sho man, im gonna get knackers deep in that bitch"

"knnnnackeeeers deeeeep"

wade in knacker deep

Formly to Have sex with a girl, also used in the context of getting something done.

Example 1
Person 1: she's fit youth.

Person 2: wade in knacker deep then mate.

Example 2:
person 1: I think i'll go to the bar

Person 2: Wade in then mate while your at it get me a pint too.