You're gonna have one in your mouth, smart ass.

[Technically true, though some people still call it an "octopus tail" when discussing merfolk. They're wrong. Just keeps everything in perspective, as octopus arms could make people think the human top has, well... tentacles too.]

Wow. Did you have anything else obvious to point out? [Katsuki drones at him before swinging his tail and "accidentally" shoving a wave of water at Izuku.] There's a whole damn city out there.

[Wherever "out there" was.]