Verb: the act of fist pounding someone and continuing to duck your fist underneath his. While performing the act you would say turtle as your hand is going below. Causing the person on the receiving end to appear stupid.
"Oh dude way to go" (offer fist pound and continue with turtle motion) "oh shit, I got you with the turtle bitch"
A: I wonder what is going on through John's head B: I dunno, I didnt know he was like that..
'John walks up'
John: Hey guys whats up
A & B: Woow, fucking turtle...
when your fucking a girl from behind, you throw a blanket over her head, when she peeks out to see whats going on you punch her in the back of the head. she then retreats under the blanket like a turtle into its shell