I can turn my skin to steel.
From Create Your Own Story
"I can turn my skin to steel," You demonstrate.
"Well, then, I think I'll call you Colossus Jr." Elixir says.
"Please don't," You reply.
"Okay, then, what about Metal Lad? Or Steel Man? Or what if you learn magic and become the Steel Sorcerer?" Elixir suggests.
You:
Ask if a codename is really necessary