The Reverse turtle is tucking the junk under the ball sack leaving only the head sticking out resembling a turtle in its shell. Also on The Waiting scale it is worth 3 kicks.
Oh man he got me with the reverse turtle and then kicked me 3 times!!
When two males (at least one that is uncut) touch the tips of their dicks together and the uncut one rolls his foreskin over the other male's dick head. This would resemble the reverse of when a turtle hides its head in its foreskin-like neck.
While I was pissing in a urinal at the bar, the two guys next to me started to reverse turtle!