Your hardest kick to the nuts, chances are he thinks he's gonna have an easy time kicking your ass and will be too cocky to think your gonna kick him in the nuts. Then a knee to the face, and when he drops to the floor a kick to the face or ribs depending how much you hate him.
Then throw him a bit of smack talk and walk away
Id always go for a kick to the nuts at a medium to short range, maybe when he gets in your face or whatever. Or a knee to the nuts, knee to head and a few kicks when he's on the ground.