He probably liked your shirt. If kids are a young age, then if they see a shirt of some sort of animated character, like a cartoon character, they will really like it, and guess will say that it's cool.
I actually remember back in the summer, me and a few of my friends were just hanging out, talking to each other. We were at a camp so bear with me. Anyway, one of my friends was wearing this foxy shirt that looks like it came from fan art. We are chatting when this young kid in a younger group goes up to us, and I am not stuffting you, he literally pointed out the shirt my friend was wearing, simply because it looked friendly. Then again, it was probably just FNaF, but still.
I mean the kid looked like he was 12-14. So I'm sure he either watched a youtuber play it, played it himself, or misrecognized me. I'm willing be bet the latter most because that's exactly how my younger brother knows a lot about Undertale.
