He's not Flash but he's fast and his name is Jay

from Run-D.M.C. – Peter Piper Lyrics on Rap Genius

Meaning

Jam-master Jay isn’t Flash (neither the superhero whose power is speed nor Grandmaster Flash, DJ for the Furious Five) but is still fast.

http://www.flickr.com/photos/66530616@N08/8584747450/in/photostream

Here is an image of Grandmaster Flash, to whom Jay is being compared. This is a watercolor painting by HaringDMC.

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