The act of fucking a woman in the pussy with your cock while simultaneaously sticking your balls in her arse, known as "keeping the dog in the bathtub" because it is as hard to pull of successfully as keeping your dog in the the bathtub while washing it.
The sexual act of placing both penis and full scrotum inside the anus of your partner. Said act is aptly titled as pertaining to the complication factor of performing the act of keeping a Dog in a bathtub.