So when that happens, this works in Keynote, PowerPoint, it works in every program, all you do is hit the letter B key, B for blackout, to black out the slide and make everybody look at you, and then when you're ready to go on, you hit B again, and if you're really on a roll, you can hit the W key for whiteout, and you white out the slide, and then you can hit W again to unblank it.