Yoruichi Shihoin and Kisuke are doing some basic training together. Yoruichi tells Kisuke not to peek even though she shows him more than she already should. That’s were Urahara decides that it’s time for a lesson. At some point you have to do it anyway (he thought to himself). So they start their own little adventure with lots of full color sex scenes and top class sex positions.
P.S. I believe that Shihoin knew from the very beginning that it was his dick, she just felt like sucking on it for a while longer 😉