To show no mercy or compassion, kicking someone while they're down.
Guy 1: Hey man, I really want to break up with this girl but she really likes me and she's been talking about suicide lately.
Guy 2: So what? Sweep the leg, man.
1. (v) An illegal method used by the Cobra-kais to hurt Daniel Larusso and remove him from the tournament. 2. (v) When something totally kicks arse. 3. (v) A term used to describe a beat-down arse-kicking.
(2) I thought about eating chicken, but a hamburger would really sweep the leg.
(3) If Steve doesn't watch himself he's gonna get his leg swept.
When you do whatever you have to do to win, short of cheating, but playing dirty.
This derives from the final fight of "Karate Kid" where the main character's leg is broken and the evil Sensai instructs his student to "Sweep the leg" out from under him to win.
If the pitcher wants to get past a good hitter in baseball and throws a fastball at his face, making him walk, and possibly taking him out for the rest of the game, that is an example of "Sweep-the-leg"