Sam senses a presence. [Cue the theme from Jaws.]
Do you sense it, too?
OH MY GOD, IT'S THE DOG.
You'd think Sam would be used to Dobbs by now, since they've been roommates for almost eight months. But no, his face still lights up with idiot glee when Dobbs comes within face-whapping-with-the-tail distance.
One thing I can tell you: if I ever see Sam make this facial expression when he's a teenager, I'm searching his room for drugs.