"Why am I naked? Why aren't you! We were about to... uh... you don't um, remember? And Transia? What are you talking about, I thought we talked about you using magic while making out. It always ends badly..."
He stands from the crater and stands shakily to his feet. Understandably both he and his erection have lost the mood. With a moment's concentration he shifts his bare flesh into his uniform. He figures if Billy has his costume on then there has to be some kind of reason. Besides, he's going to have to explain to someone why there's a man-shaped crater in their driveway. Those kind of explanations go better when people can't see all your gingerbread and everything.
"Okay, you got five minutes to explain this Billy, and no magic, my face still hurts and I think I got a rock pebble caught between my ass and my uniform. So you'd be better served to make like you're outta mana and talk fast."