Years ago, with the old San Jose Symphony, for a Pops Concert, we had Cleo Laine & John Dankworth. These two do a GREAT show and it was a pleasure being on stage with these two jazz legends. On one of the tunes, there is a tuba solo that has an optional double high c (above the "Encounters II" high Bb). There are two alternates, one of which goes to 3 ledger line g, and the 'easy' one which falls to middle c. I CAN play the double c, but it is a little more that a squeal some days. At the time, I was preparing "Encounters," so my falsetto was in good order and singing & playing was in my wheelhouse at the time. I practiced Mr. Dankworth's solo with the 'safer' high g options. But at the rehearsal, I just couldn't help myself and at the last minute, I SANG the double c, clearly and strongly as if Pavarotti himself were belting it out. Of course, the colleagues to my right (the trombones) were laughing their asses off because they knew what I had done, and, honestly, it wasn't pretty. Dankworth's eyes LIT UP and he stopped the orchestra. He said, "Ladies & Gentleman, I have NEVER heard a tubist play that note with such strength & clarity before. Well, done!"
Each of the next 3 nights, I did the same, and each night I got John's thumbs up.
Ya just never know.