And so on and so forth. When it's reflected off the ceiling and go straight down to the bottom border it simply disappears and the next bubble in queue can be launched. Useful when you wanna ditch useless bubbles if you have that kind of space in the middle. Now you can fire the next one. As I said before, bubbles don't always bounce back off the ceiling, here's a scenario where it'll appear to be stuck to the ceiling.
G get harder.