He decides to "build some confidence"

Despite the thought of walking out of the locker room and into some exhibitionist journey making John fully erect he couldn't deny that the shame would probably kill him. Sitting in the locker room butt naked he already felt a bit embarrassed at the likely chance that a woman could walk in at any moment. Getting up John decides to wait in the shower so if someone walks in he can see their reaction to the big reveal. (or in his case tiny reveal) Thinking in the showers he realizes that he can gain the courage to go on his little exhibitionism journey by showing off to the women that walk in. Taking the shower head off the wall he sets it to cold and blasts it on his dick shrinking his already pathetic dicklet into a tiny button. All that awaits him now is the wait itself for someone to walk in.