He pounds her fist gently and then pulls his hand back in a mock explosion complete with sound effects. The sound effects are the most important part, obviously.

"I can be serious. I'll be serious when I meet them. Promise." Well, he'll try very hard to be serious, but it can be hard to contain that type of excitement. Robots. Not droids, but he can't call them robots, either. "Be the most serious motherfucker you know. Call 'em whatever they want. All polite."