Can You Dig Elvis?

Dean woke up to the sound of muffled sobs. He quickly exits his room in the bunker, only to find Sam, in the dark, with chocolate bar wrappers around him, sobbing over his laptop.
"Sammy?" Dean asked. Sam turned to him and just stared. Sam starts sobbing even more.
Dean quickly rushed to him. "Are you hurt? What happened? Are you ok?" He asked,worried.
Sam looks at for a little bit longer. "Can you dig Elvis?" He asked randomly.
Dean looked at him even more worried, afraid the Sammy has finally lost it. But he answers the question.
"Elvis? I can dig Elvis."