The hat, based on Seth Green’s Robot Chicken, is available free to anyone who signs up to receive the Adult Swim newsletter before July 4, 2012.
The hat is only the beginning of a collaboration between the two giants it appears.
According to a promotional page, newsletter subscribers will “be the first to know when we have MORE new stuff coming down the ol’ Steam pipe-hole… Because this ain’t the last you’ll hear from Adult Swim and Valve. Stay tuned.”
An FAQ on the promotion addresses speculation that the two are collaborating on a Team Fortress 2 cartoon, with the simple answer of “go ask your mother.”