Carter flips through charts and runs into Lisa; he comments that his day got better, and asks whether hers did, too. Still aglow with the light we call Luka, she chirps, "I think so!" Dr. Dave regales Frank with the tale of Mr. K.'s spontaneous combustion, and Carter remarks that there's no such thing. Dr. Dave snorts that there was "no lighter, no matches, no nothing" (all REX), and Frank backs him up, claiming that he saw something like it as a cop. Mark asks Carter how his first day back was, and Carter says it was fine, but slow, which Mark says is good. He asks if Carter's done, and Carter says he is "officially out of" there. Mark blandly says "there's just one last thing to do," and hands him a cup. Carter regards it, momentarily stunned (and a bit stung), but he says, "Sure," and makes for the washroom. "Coming with me?" he asks Mark, who replies, "Those are the rules."
In the men's room, Mark says that he has to witness the whole process: "Trust me, it's no treat for me either." Carter goes to the urinal, and Mark stands beside him, with his back turned. There are none of the usual sounds of urination. Carter stares at the ceiling. Mark asks if Carter's seen any good movies lately (yeah, way to act casual, Mark), and Carter curtly says, "No." Mark stares off, and then offers to run some water. Carter stares down as he completely fails to pee, and then...finally pees. Ah, blessed release -- Carter with the bladder, and me with the end of the episode.
Next week: Benton finds out that Romano's talked shit about him to every hospital in town.