-A person that only gives 50 percent of themselves in everything that they do.
-A person that finishes only 50 percent of something that they start.
-A lazy person
First mentioned by Pauly Shore in the 80's, but made popular by Larry the Cable Guy's self deprecating humor.
Also used in some of Jay Chandresekhar's Broken Lizard Industries movies
Pauly Shore: "Why does Larry the Cable Guy always do everything half assed?"
Jay Chandresekhar: "I dunno, he never finishes anything"
Larry the Cable Guy: "That's why they call me Mr. 50 Percent...giterdone!"