He doesn't take the nickel right away. Instead he stares at that wallet for a moment, then at the coin, before slooooowly taking it... using the pair of tweezers he's pulled from his pocket.

Calvin holds the coin gingerly away from him, wrinkling his nose. "Ugh. I'm going to have to decontaminate this before I spend it anywhere." With that, he holds up a little plastic sandwich baggie, drops it inside, and seals it in a hurry.

"All right," he says. "My great idea is to find a shrink ray, and zap that thing-" he points at the emitter eating up her forearm- "down to a better size. Whatever it is, it looks like it would be really inconvenient to run around in. You should make it smaller."