The wild style is an item of clothing worn by Greiger. It can also be worn by male player character's in some video games. The female alternative to it is the race queen outfit.
In Yu-Gi-Oh! 5D's World Championship 2010: Reverse of Arcadia, it can be purchased from Chihiro at the cost of 5 Star Chips.
This set can be found in Yu-Gi-Oh! 5D's World Championship 2011: Over the Nexus.
Male Player (WC11) in Wild style set.