Viktor is wearing a pretty typical raven mask, the black feathers sticking out in every which direction, decorated by very bright sequins. When he's tagged by Papyrus, he's a bit tipsy, so he naturally plays along. And much like the bird whose mask he is wearing, he caws back at the stranger before following after him, almost tripping on other guests along the way.

You'd think a bird wouldn't chase after a "tiger." Oh well. "Wait, come back! That's not fair!" He's laughing despite it all, trying to "trick" the other person to come back out of fairness.