Everyone (99% of his personal circle of friends, and more than 55% of his friends of friends) thinks that he is cool; they enjoy his company, particularly the female ones.
Please note that, the term is not related to a man literally inserting his scrotum in/out of a woman's mouth when he is plowing her. Even if she is making pop-like sound in the process.
Guy B: You know it!
Guy C: Just look at (Guy B), chillin' with those hot girls like he doesn't even care if they have boyfriends or not.
Guy D: He's such a ball-popper.
Guy E: Hey, (Guy B)?
Guy B: 'Sup?
Guy E: Where were you yesterday, you did not show up in our group meeting?
Guy B: Sorry dude. I ball-popped all afternoon, so I forgot all about it. I won't forget to come in the next ones.