Wow. I don't want to believe you, because that sounds like nonsense. But. It's not the kind of nonsense you make jokes about. [He'd know, between a lifetime and more recently specifically compiling a list of that kind of thing, for making his framework of How Papyrus Behaves.exe recommendations. At the very least he has to concede Sans believes it. He shakes his head slowly.]

I can't believe... you've found evidence, that your idea last night was right. [Normally, he might not want to hurt Sans's feelings by asking something so bluntly. But normally a lot of things that should happen don't, and sometimes people steal things without warning, so clearly some of the usual rules are off.] ...Did you know, last night? Did you... do this? At some point?