It's a fantasy role-playing game.

DM: You are Caleb Widogast, a human wizard . You are the member of the famous group of adventurers. Previously, During the second watch, you is awakened by his Alarm and sends Frumpkin to investigate. Frumpkin sees a merrow has emerged into the chamber, who sees both the bodies and Frumpkin, and throws a spear at him, but you is able to bamf him out safely.
DM: The loudest cat you've ever heard. Frumpkin is the neighborhood cat in heat at this point. He makes his way down through the tunnel. Make a perception check with disadvantage for Frumpkin because he’s now coming around the edge.
Player: Someone told me that cats have advantage on perception. Are they full of shit? You’re my DM. Would it cancel out, is why I'm asking?
DM: Would it cancel out? I would ask you to keep the stats of your cat on you for future reference.
Player: I will.
DM: They have advantage on wisdom perception checks that rely on smell. I'd say sure.
Player: So cancel?
DM: Yeah, it'll cancel out, so a straight roll.
