Fowler, irritated by Bennett's mention of Judd, snaps "Don't mention Judd to me!", upon which Bennett innocently repeats "...Judd?", and then proceeds to "absentmindedly" (and loudly) hum his friend's name while ironing his uniform. "Juuudddd... Judd Judd Judd... Juddddd..."
The entire sequence with Bennett deliberately losing the military inspection is Cringe Comedy gold.