Reheating a hard-boiled egg is as simple as nuking it for a couple of minutes. That is, if you don't mind the explosion.
In response to a lawsuit in which a man claimed to have been burned after an egg exploded in his mouth at a restaurant, researchers recently set out to answer whether microwaves can turn hard-boiled eggs into edible explosives. Of the nearly 100 eggs they tested, 28 exploded after being poked with a meat thermometer. That's why you should probably just eat your leftover eggs cold from now on.
Check out one example of why microwaves and hard-boiled eggs don't mix.video-player-present
(via IFL Science)
I'm pretty thankful I've never reheated eggs in the past. Just imagine that happening in your mouth.