Larry the Cable Guy on Blue Collar TV uses this as a sort of catchphrase. It's meaning is pretty much universal, but is mostly used as a way of agreeing with something enthusiastically.
Son: Hey Dad, do I plug in the leaf blower now?
Dude1: Dude, that chick is so hawt!
Host: Table for 2?
Married Couple: GETERDONE!
no,no,no. You folks got it all wrong. Trust me I was there when this happened. To deflower a young woman.
The girl wanted me to have sex with her friend. She shut the bedroom door and said," When she comes out of there I want her split like the Grand Canyon. Geterdone."