Panel 1: As Mrs Divot and Trevor leave, John speaks to her as if he's talking to her on the phone when he says "Yes, Mrs Divot, call us any time. No, we won't overcharge. If you're unsatisfied, call us any time. Yes, my home number is listed."
Panel 2: As they head out the door, John tells his receptionist that he likes to make small notations about his patients on their charts before telling her to write PITN on Mrs Divot's chart.
Panel 3: She asks if that means "periodontal inflammation - treatment necessary."
Panel 4: He replies by stage-whispering "pain in the neck." This is because this is a family strip and we cannot have him put PITA (standing for pain in the arse) on her charts.
Summary: Now that Mrs Divot has served her purpose of showing us how John deals with the disruptive patients, let's see him interact with people who don't try his patience. (See, Lynn....THAT is how you repeat words.)