Be careful what you wish for...

[Hookbill the Goomba]

Remember to quote the wish you are granting!!!!!

The "Arms" thing came from a joke running in my family. Zombies in modern films don't say "brains!" like they did on old ones, but just groan. Their groans sometimes sound like "arms!"

Anyway,

I wish I had a pony named Bill

Your wish is granted. But due to Gandalf asking for your wish in writing, you accidentally write "Phoney" and so he gets confused and turns you into an old man called John, who just calls himself Bill.

I wish that Beren had taken two Silmarills!