She almost looks a little bit confused by his answer - or rather, by these very specific options he's giving.

"No, I mean actual monsters!"

.. she's pretty sure that's what she means, anyway? Now she's kind of confused whether they're working with the same definition of monster here..

"You know, like the kind you'd see in a video game?" Maybe that makes more sense to him. It's definitely how Minako would categorize the monsters in this place, and she gestures with her hands as if that makes what she's saying any more clear, despite the gestures being very vague. "I don't even know why you'd think of a guy in a rhino costume!"

H-Has he seen one of those before? Why would a guy even dress up as a rhino?! Is it a Halloween thing?