[Sayori's answering grin is so delighted that it's hard not to clock it as a little mischievous. Is it time to break the news? He doesn't seem to have figured it out yet, so she thinks it's time.]

Well, if I'm gonna be living here for now, I need to get into shape so I can run away from creepy mannequins and stuff!

[Wow, she sure does not seem bothered when she says this. She barrels on without any change in expression.]

And it'd be pretty convenient for my Uncle Papyrus to teach me how, right?