I always wanted to learn to play electric guitar, electric bass and upright bass. Never happened. A friend tried to show me to play power G on his guitar. Couldn't get my long fingers to the right position. Oh well.
Me too! Air bass, air trumpet, sax, you name it. Not many people get to see me do it because it usually happens at home. Several people thought I really could play guitar, including some guitarists. I would just chuckle and say "I'm only guessing what the real guitarist is doing."
These days at work, a lot of people get a kick out of seeing the crazy old man with headphones moving to the music as I blow leaves, collect piles of leaves, etc. It helps me stay focused on getting the job done right and moves the day along.