slip one past the goalie

To successfully have sexual intercourse with a woman who has told you no. (Rape)

She told Brian she didn't want to have sex last night, so he tried to slip one past the goalie.

let one slip

To shoot someone.
With a gun.
Fool.

Pull out the 9.
Pop in the clip.
And let one slip....
Into these crazy fools

slip-Ons

A Person so unintelligent they can not tie shoe laces so they resort to wearing slip-ons.

Used in an office setting you can then define a team of Slip-Ons into their own names such as :
Master Slip-Ons - someone who makes mistakes constantly
Senior Slip-Ons - someone who has been there the longest
Madame' Slip-Ons - a lady Slip-On

Bill, Can you ask master Slip-Ons of he wants coffee?