What are some interesting small insignificant theories that you have read or come up with?

Whenever we talk about One Piece theories, we mostly talk about big ones like guessing heritage of an important character, trying to figure out what One Piece is, what's on Laugh Tale etc.

But what I want to hear are theories that are insignificant to the plot/not as important. Like Calico Yorki possibly being alive or Sasaki possibly being Kokoro's son (fishmen with green hair that drink all the time).

What small theories do you know?