Granted, but the new weight of the stone on the walls causes a critical structural failure of the cave/building/whatever you are currently in. You are crushed.

GRANTED, and you are in the front row of the concert, eating your sandwich. But then one of the performers decides to jump off the stage and bodysurf the crowd. He lands near you and the crowd begins to move him in your direction. You put up your hands to help keep him aloft and drop your sandwich on the floor. You slip on the sandwich just as he passes over you. You both fall and he lands on top of you, causing your skull to smash on the hard concrete floor. You die.

Granted. You are on it after it was blown up and you suffocate because the atmosphere scattered in the explosion.

you become a better writer, but you are hit by a bus before you can do anything with it.

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I wish i could finger A Minor (if you know what i mean...)

Granted, but it gets so cold it kills cells, then burns them do to extremely high temps.

I wish America was out of debt.

Granted. USA has no debt now but then Russia nukes them.

You are immortal, but only for 5 minutes. Then you die because of wounds you get because you couldn't feel pain.

I wish i could troll here without breaking the rules.