You can read here:
Dick Suck is a meme referring to an annotation shown during the introduction to the character of Zapp Renfro within episode 2 of the anime, with one of the introductory annotations referring to him as a “dick suck”. Due to the humorous nature of the comment, the term grew in popularity among fans, and is often paired with fanart of the character.
However, it's mostly a pun on baka as mentioned on Reddit:
I think it actually says "Baka Baka".
Yep, the kanji is 馬鹿 (baka) and the katakana says "baka" too.
As for the reason of its official translation being that as well, it seems to be for nothing more than humor purposes like senshin points out in the comments.
Something similar to this is:
Chain Sumeragi being labelled as a "shawty"