A 5 year old boy with Leukemia was granted his wish to become Batman by the city of San Francisco.
http://abcnews.go.com/Entertainment/wireStory/san-francisco-calling-batkid-fight-crime-20901893
Of course I was able to think of a different wish that a kid might have ...

Anyway, he had a great Batman Cosplay in a Lamborghini Batmobile!