Anyway what about O stands for Oden?
I don't think Rocks stands for anything. It is just a name that will likely thematically fit once we see the full picture.
I mean Ace's Crew was named the Spade Pirates, no one predicted that, but it did fit since the Ace of Spades is a playing card. And it represents death, and then Ace died...
Rocks will be a thematic fit, not an abbreviation of anything. I think so, because I think it is fairly likely that Newgate and Bakkin were in that crew as well and then the letters don't match up. They are said to have been on the same ship
40 years ago. I think that ship is the Rocks ship, because I don't think the pacing permits two seperate flashbacks of 40 years ago. One Piece is getting closer to its end, things are rather falling together than going in different directions.
By the way, if what I believe in is true, then Garp's story is kinda the antithesis to Luffy's story, which would be fun.
To become Pirate King, Luffy has to fight Big Mom, Kaido and a Gura Gura user.
To become the legendary Marine hero, Garp had to fight Big Mom, Kaido, a Gura Gura user...