Pryce is reading aloud from an expense report, and I guess people generally find him so likable and charming that he's forced to take measures such as these to lower their expectations. Don enters, late, and after Pryce makes a snarky comment about the same and receives a blandly witty rejoinder, Pryce wonders why Sal put in for twelve dollars more in expenses on the Baltimore trip than Don did. Well, he had to give the bellhop a good tip, no? Pryce then complains about the number of pens and other office sundries that are being consumed, and at this, Don has had enough and leaves the room as early as he entered it late. I will give Pryce credit, however, for not skipping a beat as he moves on to a mystery of a missing credenza. Heh.