I never quite understood how Flipull got its name. You don't flip anything, really, and you aren't filling anything up. Apparently, Taito doesn't know what it means either [via The Retroist]:

What action does Flipull suggest? Will I play my Game Boy upside-down? The easiest answer to all this is that no one knows how to accurately describe this game, not even the publishers.

If you've never seen Flipull in action, check out the handy-dandy footage after the jump. I lost hours to this puzzling demon in the '90s.