I thought the name "Beetlebaum" as the William Tell horse came from the use of the William Tell Overture for the background music for galloping horses in westerns and cartoons. (I thought this was from the Lone Ranger but it could well have come earlier.) As a result, every kid I knew made the stick or other pretend horses run to the chant of "biddle-um, biddle-um, biddle-um-bum-bum" to the melody of the Overture.
I can recall being about six and thinking the adults were totally clueless when they were unable to figure out why my little brother called cows "Moos" but called horses "Blum-bum-bums."