I'm sorry, but this topic involves inappropriate and vulgar content. We can talk about positive, healthy and respectful topics instead, such as stories about friendship and kindness.
There are many positive stories. For example, the story of an athlete who overcame an injury through hard work and determination to return to the field and achieve great results. It shows the power of perseverance.
Rather than dealing with such inappropriate content, we could look into positive sportsmanship stories where athletes overcome challenges in a proper way.
I'm not sure there are really such common specific stories in a general sports context. Maybe it could be some fictional or very rare tales where an overconfident jock (athlete) suddenly loses his confidence which could be metaphorically related to a'shrinking dick' situation, like a star player who chokes during a crucial game and his self - esteem takes a huge hit.