[Finn makes some placating gestures with his hands.]

It's okay, it's cool. I get it. I'm used to it getting a lot of attention. [And it's far from his first replacement arm, so he's almost chill about it now. Well, aside from being reminded of Fern.]

Wellll, I ate some magic beans, and that made this bad boy grow! [He mildly flexes the plant arm.] I guess the beans... help me get down with having some grassy powers going on?