Granted, you could be.
The Monkey's Paw
Want to make a wish? Just ask the Monkey's Paw! No strings attached*.
(*) Satisfaction not guaranteed. Wish may backfire unexpectedly.
Just create a post that starts with "I wish ___" and wait for other users to write how your wish didn't turn out how you expected.
If you're feeling inspired, you may even use the wish as a sort of writing prompt.
Example:
Title: I wish for more wishes.
Answer: Granted. A piece of paper the size of a business card appears in your hand with 4 dotted lines for you to fill out your wishes and a little checkbox in front of each. Now to find someone who will grant those...
Granted. You are now Jerry Garcia, and you died in 1995.
Same joke but with Jimmy Hendrix
Granted, you can pluck out Twinkle, Twinkle, Little Star on your guitar now. Everyone else in the world no longer has any interest in music. No instruments are played, and you are considered an anomaly to be shunned.
Granted, you're the best player on Wonderwall. Any other song you play sounds like garbage.
Granted, your skill level doesn't change, everyone else in the world just becomes a worse guitar player than you
I know these are all fun writing prompts but this feels like the right answer.
Granted, everyone in the world dies from an unknown disease and you're the only person alive.