There sure are plenty of people for Joker to subtly look at. Between the people who aren't human, the people who are literally rocks, and the people who literally lived under rocks while also not being human... Well, any glance shot Papyrus' way is just a cue for him to raise his hand and offer a question.

"That sounds like... strict teacher seating ettiquette! If the chairs are anything like desks... there's openings perfect for tails"