Wife's Best Friend 

Male Genitalia - The Cock, the Dick, the Penis! etcetera etcetera

From "The Penis Song" - in Monty Python's movie - The Meaning of Life! -
"Isn't it awfully nice to have a penis?
Isn't it frightfully good to have a dong?
It's swell to have a stiffy,
It's divine to own a dick.
From the tiniest little tadger
To the world's biggest prick!
So three cheers for your willy or John Thomas.
Hooray for your one-eyed trousers snake.
Your piece of pork, YOUR WIFE'S BEST FRIEND
Your Percy or your cock.
You can wrap it up in ribbons,
You can slip it in your sock.
Just don't take it out in public,
Or they will put you in the dock
...And you won't - come - back ! "

Wife's Best Friend by Volcanoe Joe January 21, 2009

shake hands with the wife's best friend 

to urinate

I'm gonna go to the restroom and shake hand's with the wife's best friend.

shake hands with the wife's best friend by sloppy Joe April 30, 2003