Sans hasn't stopped smiling as the monster starts looking more interested, then suddenly a whole lot less. He's not really sure he could stop smiling even if he tried, but he's not really interested when this is getting to be pretty entertaining. Is he spooking this guy out or what?

"nah. made of magic, just like every other monster out there." He studies the monster closely for a minute, thoughtful. "now it's my turn to ask a question: what kind of monster are you?"