bifkin's bridge 

The area between the scrotum and the anus.

I've been for a 10 km run and bifkin's bridge is really sore

bifkin's bridge by e-bow-the-letter May 1, 2016

Biffin's Bridge 

The area between the vagina and the anus..cross if you dare!

Well it slipped out of the hole, across Biffin's Bridge and up the ante!

Biffin's Bridge by Tracey August 29, 2003