Peeling hard-boiled eggs can be nightmare if you don't cook them right or try to pick off the shell piece by tiny piece. A quick shake in a partially water-filled glass can do the deed cleanly in a matter of seconds.
In this video from YouTuber MicahMedia, you can see how fast it really is. Grab a glass that's small enough for you to hold between your thumb and the rest of your digits. Place the hard-boiled egg in the glass, fill it with about a centimetre of water, cover the top of the glass with your fingers as demonstrated, and start shaking. The trick is to shake it over the sink so some of the water can escape through your fingers and not get all over the place. You should be able to reach in and pinch the egg's shell right off.
Peel a boiled egg in a glass of water [YouTube]