Happened to me as well. When I arrived for my first orchestra practice at Normandy Jr. High School in St. Louis... I was 20 minutes late and was assigned a huge B-flat upright horn. Weighing barely a hundred pounds and five feet tall... I had the biggest (musicalβΊοΈ) instrument in the concert orchestra. Despite the hopeless odds, including my limited lung capacity, my folks hired a tutor and I was taking tuba lessons.
Because of the disparity between my physical size and requirements of "the beast" the band director, Mr. Duncan, obtained a stool for me to sit on and commandeered a waste basket which was inverted and used to hold the base of the tuba.
All worked fine until the day we were performing at a neighboring high school assembly and Mr. Duncan... inspired by a rousing reception from the audience, ordered us up onto our feet and told us we'd march around the auditorium of seated students and then back up onto the stage all while playing When The Saints Go Marching In. Unlike it's cousin, the Sousaphone, the upright tuba was never designed to be played while walking or marching. I threatened to resign after the ordeal was over, but to keep me in the orchestra, Mr. Duncan compromised and made me assistant conductor!
I still have my baton packed away somewhere. 1-2-3-4