In high school, we always had theme days during the week leading up to homecoming in the fall. They varied every year, but Friday of the pep rally was always the same: the freshmen wore white, the sophomores yellow, the juniors green, and the seniors wore togas. When it was my senior year, I had a lot of the cheerleaders and volleyball players in gym with me, and we happened to have gym on toga day. Of course, we didn't bother changing into gym uniforms since nobody was doing anything in classes all day. We ended up playing volleyball for an hour and fifteen minutes in our togas, watching the cheerleaders and volleyball players' boobs pop out with every set or spike. It was a fun day.
Sort of closely related, my girlfriend was very well-endowed, so it's fairly common for her to "pop out" of tops. No big deal for me, but fun for other guys at the beach and pool.
Here's a picture I took of her at the beach this summer to illustrate my point: