He turns off the shower and steps out. He takes a look at himself in the mirror, he is wearing a T-Shirt and can see below the bottom of that a yellow bulge where he has just wet. He removes his T-Shirt so he is now just wearing the diaper, he turns so he can see the back and he sees the wetness creeping up the back side.
He reaches down and rubs it into himself, enjoying the sensation.
He feels he would like to do this all day, but decides against it. He pulls back the tapes and allows the diaper to drop to the floor, which it does with an added thud due to the extra weight. He turns the shower back on and jumps in to clean himself up.