From Diablo Wiki
Before and during Blizzcon 2009, Blizzard ran a contest tied to their new @Diablo Twitter account. Fans were encouraged to send tweets to @Diablo, with their suggested name for a Diablo 3 unique item. Five names were to be selected for inclusion in the game, while the ten best entries each day were to receive one of these Diablo pins, of which 100 in total were given away.
Copyright IncGamers Ltd 2016