You think Justice League XXX and X-Files XXX are so clever? They all pale in comparison to the godfather of the porn spoof genre, 1974's Flesh Gordon. Based on the old serials and featuring stop motion special FX from people who would go on to greater fame (Mike Minor, who designed the refit USS Enterprise for the Star Trek films, Rick Baker). The film tells the story of Flesh Gordon who, along with Dale Ardor and Professor Jerkoff had to stop the Sex Ray from planet Porno, ruled by the evil Wang the Perverted.
The movie's actually a pretty loving spoof of the old serials, and the FX work ain't so shabby. The big monster you see in the trailer was known to the crew as "Nesuahyrrah" for the great Ray Harryhausen (animator Jim Danforth would go on to work with Harryhausen on the real Clash of the Titans), and in the final film it features the voice of Coach himself, Craig T Nelson.
Legendarily Flesh Gordon was a hardcore porno, but all the really dirty stuff apparently ended up in the hands of LAPD vice squad (I recently wrote about why this doesn't happen anymore. Read that here) and the version that was released was softcore. As far as I know the real X-rated version has never seen the light of day - even the special edition that came out a few years back isn't hardcore. If anybody out there knows of the existance of a hardcore version of Flesh Gordon, I'm interested in hearing from you - devin (at) badassdigest.com.