Adult Swim and Valve have teamed up in the past to create a Robot Chicken-themed hat for Team Fortress 2. The promotion was given to anyone who signed up for Adult Swim's monthly newsletter and felt like a bit of a disappointment given how both companies were hyping up the partnership.
They've since gotten back together again for something much more awesome this time around in the form of Adult Swim gear for Team Fortress 2. You'll be able to dress the Scout up as a Monarch henchman, turn the Heavy into Brock Samson or ATHF's Carl, and turn the Pyro into Dr. Rockzo from Metalocalypse.
360 degree previews of all four characters can be found at the promotional page that Adult Swim set up here. With any luck, they'll add the entire cast of the Venture Bros and Metalocalypse into the game. Keep your fingers crossed.
The new costumes are coming soon to Steam as DLCs.