Rock of Doom
The Rock of Doom is a variation of "rocks fall, everyone dies" wherein the DM specifically targets a single character that he (and possibly all the other players) wishes was dead in order to force them to play something different. The archetypal example is that the player in question picks up a rock and is told that it was a Rock of Doom, roll up a new character.
You can use the Sphere of Annihilation if you're boring, and have no friends, and people's eyes glaze over when they talk to you, and you're my dad, and you spend time on here instead of spending time with your friends.
But as sexy and interesting people like your mom will tell you, there are many creative ways to do this, aside from the standard Rock of Doom. They come in all degrees of subtlety. Putting a curse on the player that causes his character to burst into flame if he rolls 1-20 on a throw that must be repeated every round is a less subtle example, while a curse that causes the character to grow two feet of facial hair every hour is more stuble.
A particularly devious DM (Forgive me, I do not remember the source, but it didn't happen to me) trolled his party epically by describing a faint glow in an otherwise featureless room. The party members went and poked at this glowing metal, and were told it was warm and slightly crumbly to the touch. Of course, thinking it important, they took it with them. Some time later, "everyone dies from radiation poisoning". It was plutonium (even though plutonium doesn't glow... maybe it was magical plutonium). Dickish, but more classy dicking than normal Rock of Doom.
One Redditor known as ILikeToShootZombies once gave his players a cursed +2 round great shield of returning that constantly croaked with the sound of a hundred frogs for an enormous -30 on anything sound related (from Stealth and Listen checks, to simply trying to talk to people). To complete the effect he set up a speaker at the table with looped frogs croaking at annoying loud volume so the party had to talk loud as hell to hear each other. Just for lulz he even made the shield spawn a half-dozen magical constructs of frogs each time it was struck.