A guy that is very very sly. So sly to the point where your jaw drops when he does his cunning actions.
Freddy: "Cory, I can't believe you just benched 365; That's so incredible!"
Cory: "Yeah, I'm what you call a Sly Guy."
Cory: "Yeah, I'm what you call a Sly Guy."
by Backflip Guy August 2, 2009
Get the Sly Guymug.