Rhino Headbutt

When a kid in the 5th grade wearing a ridiculously stupid bike helmet bends down, points the top of his head at a random person, shuffles towards them with his arms out like he's about to fight them, and shouts the fact that he possesses something to the extent of "rhino headbutt." This has occurred once, at a block party on the East Coast, and hopefully will never repeat itself.

Nova: "Johnny, what are you doing with that bike helmet?"
Johnny: "I HAVE RHINO HEADBUTT!!"