I took a shower with Sully earlier this morning and one of his things he likes to do in the shower is fill a bathfoam container cap with water to pour it into a larger container.
But, because I was in the shower with him and obstructing the water flow, he had to look for a place where the water was running off of me. And, being a man, one of the natural places for this to happen is my cock.
So, Sully kept holding his cap up under my penis to collect the water.