An item or object that appears at first to have extraordinary value, but later turns out to be a false or fake knock-off. At the 2005 MTV Video Music Awards the artist P. Diddy gave an audience member a extremely expensive watch. It is rumored that during the commercial break, Diddy's security replaced the watch with a cheap knockoff. The Phrase was first created on the 7th Episode of the Podcast "Who's Your Daddy".
Aaron: hey Cliff I just bought a new car on Monday, and on Tuesday it broke down.
Cliff: So you got a Diddy Watch.
Aaron: Yeah, that crappy sales guy Diddy Watched me good
Cliff: What a jerk!