Board Thread:General Discussion/@comment-27524978-20160210030742/@comment-26814804-20160401021845

He says he can tell it from your face because Sans, as serious as he is at the end of Genocide, is still a comedian, and because, up until he uses his special attack, he never breaks the fourth wall. He says he can see it in your face because it would be awkward to say "i know you have died four times. i can remember past saves."