Ugh. Horn protrusion.
Plain clothes for me, though my head would probably look like Darth Maul's or something.
My superhero teammates would be like "Come on, Horn Man! Dr. Corruption is attacking the university with Spider-Bots!" and fly off, meanwhile I'm just kind of shuffling along in their wake like "Sigh... FINE. Whatever."
They're listing their powers, like "Captain Amazing! With the power of Laser Vision!", "Magnificent Girl! The woman who can manipulate physical matter with only the power of her mind!" and here I am, with "Horn Man! The man with HORNS growing out of his HEAD!"
During my intro, I'm just standing there facepalming like "Ugh... I don't believe this"
While they're off battling the villain, I casually walk right over to the Death Ray or whatever, press the "OFF" button, then the "Self-Destruct" button, and casually walk out of the lair's only emergency exit while everyone else has a climactic duel and thrilling escape.
I'd be the same size and shape that I am now, so every time we come to a flimsy but locked door, or any other situation where people would expect a Rhino-type character to charge, they all look at me and I'm just like "No."
I'm pretty sure that most of my time would be spent trying to leverage my position on a Superhero Team in order to pick up women, or trying to attract the Token Female Superhero on the team. Of course, in any case, I'd likely fail miserably.