"Huh?" Rhett almost said aloud, but forced it back in time. He felt the air around his body and actually realized that he was, in fact, naked. When he fought against Velez, damaging his motorcycle momentarily, he had regenerated from a single blood drop. Unfortunately, that meant that his physical body had been reformed, but not the clothes. And since he couldn't regenerate those too, his quirk effectively stripped him of his decency.
Since they had barely escaped that high-tension chase, and any sort of clothing would either have been looted or destroyed, he had no choice but to run around naked. It was simply the consequence of his quirk.
That didn't make it any less embarrassing—it was just something he had to deal with.
But he wasn't shocked because he was naked. He was shocked because of who the voice above him belonged to.
A child.