according to world english dictionary shaft is a slang term meaning "to have sexual intercourse with" and Sack as in a Ballsack a.k.a Your Testicles inside your Scrotum, so Shaft My Sack Means "To Be Intimate/Sexual With Ones Testicles"
Your Doing Real Good In COD So At The Lobby You Say to Them Shaft My Sack
A small piece of information. Derived from the word ken, used often in the scottish language and is synonymous with knowledge.
Person 1: "Hey I don't get this shit. How do you solve this problem?"
Person 2: "I got that one. Give me some kenlets on this assignment and I'll help you w/ that one."