Damn, Naruto got Sasuke'd in this!
That aside, I wonder if this is really a Japan thing like everybody keep saying.
I don't know how tight office worker rules in general are, and I don't think keychains can be that big of a deal most of the time (I can think of some teachers who'd probably mind back in my old school though), but this is one of those things right.... the "you're an adult now, don't waste your time doing this." I know something similar happens with me and old cartoon like Spongebob and Naruto. It's not from everyone, but there's a feeling like you're being judge for it.