[General] Escaping up her tunnel

[patran]

Dear Teachers

I don't understand the expression "Wouldn't mind escaping up her tunnel" in the following context. And, what is the difference between "escape" and "escape up"?

Brent talking about Donna:
“Her dad’s not only a copper, but he’s a bloody big bugger isn’t he? So hands off.”
“I’ve got something she could take down in evidence!”
“Oh, don’t worry about this lot.”
“Do you wanna receive some swollen goods?”
“I wouldn’t mind escaping up her tunnel!”

Source: The Office (UK), Series 1, Episode 2.

Regards
Anthony the learner

 

[Tdol]

There needs to be a preposition to connect escape to tunnel- you escape from prison, escape through as tunnel, etc. Up is used here as it has a sexual innuendo.