Marty gave her a slightly wary look when she mentioned a brother. But in all honesty, he'd expect to get his ass kicked for messing with someone's younger sister. "How many siblings do you have?"
Part of him was wondering, just in case he ever wronged her, how many people he'd end up having to avoid.
"Money doesn't do any good anymore. What would you pay me with?" He laughed at the idea of an actual costume. Could be fun. "I might have to ask her sometime."
His expression turned from intrigue to absolutely horrified in a manner of seconds. "Yeah, I think I can do without a sidekick. As sad as it makes me, I do not make the qualifications to justify a Justin Bieber song. Sorry."
He definitely would don the costume, maybe even outside of Halloween. Marty wasn't afraid to look like a complete and utter goofball if it got a good reaction.