According to some (e.g Slayton) it was the
PR people in NASA who had a fit about Apollo 9's callsigns of "Gumdrop"/Spider" and also the 10 crew's choice. TBF a bit of thought did go into the names on 10, Snoopy (the cartoon dog) had been used by NASA as a flight safety emblem for several years prior to the flight so was in some ways a reasonable choice, and once you've got Snoopy you sort of logically end up flying him with with his mate...but after that it was indeed decided names had to be dignified. As for 11 according to at least one account (Farmer and Hamblin, "First on the The Moon") the crew decided that an American Eagle should go on the mission patch (badge), and then decided that "Eagle" was also a good callsign - Columbia was then chosen as it was suitably American.
BTW Duke always admitted to having trouble with saying "Tranquility Base" because like everybody else in that room he was struggling to say anything just post touchdown ( even Gene Kranz was lost for words...).