Lucky Shirt

Source
This item is sold by Lenny "Fingers" McCoy in Stormwind Harbor for, but only during the quests To Be Prepared (Alliance) or The Battle for Broken Shore (Alliance).

Bugs
Although the item is an Bind on Equip shirt and is included in the Appearances tab, it sometimes is displayed as  with no soulbinding. It's suggested that you try re-logging and/or clearing your cache to correct the tooltip error.