Almost immediately, the sensation of screwing up threatens to overwhelm Sans' normally placid expression. Hands up as if to physically hold Asriel's tears in, he swallows as hard as a throatless skeleton can manage.

"Hey, hey, kid, I didn't mean--I didn't mean to stir up bad feelings or anything. I know it couldn't be easy." His voice is higher than usual, and much faster. With a cracking laugh, his grin widens. "Wanna hear a joke?"