Your wish is granted. The first time you actually try, the fire shrivels your lungs into nothing but desiccated husks of what they once were, the flame traveling through your windpipe and burning your body, cooking your organs, roasting you alive from the inside out.
You do, however, look really cool when this happens, and you're auto-cremated in the process.
I wish I was pretty (oh so pretty), I wish I was I was pretty and witty and gay.