I was working on a semi-professional production of 42nd Street, as a rehearsal pianist. The production used all the original staging/choroegraphy, the touring sets, etc. Since I wasn't actually playing in the pit, I brought my then-boyfirend to come see it with me. I had to kinda drag him to the show kicking and screaming lol, because although he liked some musicals, he was convinced he'd find this one too hokey and he really didn't want to go.
So there we were, and the Overture starts, and we get to the iconic moment where the curtain slowly rises from the bottom, revealing "those dancing feet" little by little. My boyfriend audibly gasped. And history was made. ;-)