Growing up with an Air Force officer as a dad, he loved teasing all the other branches of the military. He was an ROTC instructor for one of his "jobs" for a few years. In his classes, he had one hard and fast rule. The words for army or navy were not allowed, they had to just be spelled out like profanity with kids in the room.
Even at home, we just got in the habit of spelling out those "bad four letter words". One cadet asked about the Marines, and figured out to spell it out, and not say that word. Dad's reply was the Marines are owned by the navy, so they don't even count.
Many years later one of his former cadets was a captain, and giving a presentation to a large group of Generals and other higher ranking officers. Part of the presentation was comparing how a procedure was done in other branches. He ended up saying both army and navy in a sentence, then he looked at my dad and said sorry sir, and continued. Dad had to suppress a laugh, and everyone else was confused as to what the apology was about.
He said one of his missions was a load of mattresses in a C-124 going to some remote island base. All the Army guys had been sleeping in sleeping bags on the ground for weeks before they arrived with a large plane stuffed full of mattresses for the beds that had been brought in already. He said the Army officers were very happy for the delivery, and said they would buy the Air Force crew a round of beer that night, and make him Army for the day. He said for free beer, he bent his rule.