Hajime no Ippo

Hajime no Ippo aka Fighting Spirit is a manga and anime series about boxing about a high school student named Makunouchi Ippo.

In one episode (number to be found) Ippo is in the shower and wearing a towel, but Takamura insists that like the others, he bathe without a towel.

He assumes this is because Ippo is not well endowed and shy about being small, but it turns out to be quite the opposite.

Ever since then, there is an 'elephant in the room' whenever the topic comes up.