Position similar to the doggy style, but one that still allows for deep anal penetration, and oh so fulfilling thrusting action.
Not all that complicated, nor all that pretty, but certainly functional.
The Receiver (the one being penetrated) is on all fours.
Their head is buried into their arms, and the legs are closer together, than in the doggy style position.
One's tushie is upraised, which allows the Giver (the one doing the penetrating) a good aiming spot.
It also allows for an easy penetration, as well as allowing for good thrust control, once they have penetrated the Receiver.
The Giver generally kneels, for this position.
The hands are placed on the hips of the upraised buttocks, to help keep the Receiver steady, while being penetrated.
Not what you would call a romantic sex position, but certainly functional.
Turtle is also a British slang term, for a woman's genitals.
Supposedly derived from the term of endearment, turtledove.
Turtle is also used to denote a male penis, that is uncircumcised.
The reference is that when the person becomes excited, and sexually aroused, the head of the penis then appears, from under its protective covering. (foreskin)
Similar in nature to how a Turtle will poke its head out, and withdraws it to its shell.