The act of catching someone pretending to be performing on stage.
You're all by yourself, going about your usual routine, maybe at home or in the office. Suddenly, a song comes on the radio - or perhaps just a song stuck in your brain - and all of a sudden you feel like dancing around and/or singing at the top of your lungs! You might even grab your Air Guitar and let The Power of Rock move you. You're the big star shining on stage in front of your adoring fans! You're lost in the music and the movement! You're... ...you're suddenly staring at the roommate, relative or significant other who's been watching your every move with amusement. Dejected and embarrassed to no end, you try to slink away. Maybe you need to put some clothes on. You hope and pray there was no video camera capturing all the action. You may even try to explain that it's Not What It Looks Like. However, it's PRECISELY what it looks like... you were all caught up in letting your inner pop star loose. And there was at least one person either shocked, dumbfounded, or hey, even applauding. Closely related to Sorry to Interrupt. A non-sexual variant of Caught with Your Pants Down. I can provide an example from my own webcomic... where Matt sings the Ting Tings while an amused Cassie watches inconspicuously. I'm also open to other examples (I KNOW they're out there, especially in sitcoms) and a better name for this.