Dear I'm not sure and too embarrassed to ask anyone, lol,
Popping your cherry means, "breaking"/tearing your hymen. The hymen, as defined by members of the world wide web, is "a membrane that partially closes the opening of the vagina and whose presence is traditionally taken to be a mark of virginity."
It's important to note that a woman's hymen can and often is torn well before sex. It could be from bike riding as a kid, gymnastics as a young teen, stunt doubling for Charlize Theron in college or anything in between. But, the term "popping your cherry" is shorthand for losing your virginity. If you'd like, you can also start calling it the Hymlick Maneuver (FG™) and impress your friends.
Here's a simple example of an exchange using our newly defined term: Please feel free to construct your own exchange in the comment space provided below.
Susie: Say Jen, how old were you when you got your cherry popped?
Jen: I was 22. I bled very little, too. Perhaps it was because I was such an athlete and vigorous masturbator for years prior. Or maybe because Robert has such a miniscule penis and we took things very slow and gentle that night.