凡 mediocre

as in "You can get a BONer from even mediocre porn."

Let's call the single dot inside the diaper a tiny turd. OK? Great. Aaaand, all together now,:

A mediocre man walks around with a diaper with merely a single turd in it.

mediocre ★★☆☆☆
平 (equal / level) + 凡 (mediocre) = 平凡 (mediocre)

commonplace, ordinary, mediocre (i.e. rapping about rims)

ordinary person ★☆☆☆☆
凡 (mediocre) + 人 (person) = 凡人 (ordinary person)

an ordinary person, a common mediocre person.