Signed
From The Giant: The Definitive Obey Giant Site
Although many prints are not numbered, almost all prints are signed. All prints sold from the Obey Giant website are supposed to be signed. However, a slip-up in 2005 caused a few MLK Jr. prints to be sent out unsigned.
Examples of other unsigned prints also exist. Marilyn Warhol and Vicious Subversion, unsigned, both appeared on eBay in 2005 from a vendor who re-sells material from Obey Clothing sample sales.