the male version of the cameltoe. when a man wears tight pants and the penis and one testicle is separated to one side of the seam whilst the other testicle is on the other making the shape of a crabclaw
While performing doggystyle sex you insert both of your thumbs into your partners vagina, and place your index fingers on her ass. Then you roll your thumbs upward to spread the lips wide and raise her ass cheeks, making a perfect seal and to achieve maximum penetration. Hence your hands look like a crab's claw.
When I was banging Goldstein's mom from behind, I applied the crab claw for maximum penetration.