The Batman and Robin film. Yes its an awful film. Its stupidly bad, however its just so unintentionally funny. The film reminded me of the old Adam West Batman series, only with a bigger budget. As an actual film its terrible, however as riffing material, awesome.
I also like the Deadliest Warrior T.V series for similar reasons. The show is stupid, the results and their testing methods are stupid, their history is straight out of the movies (i.e inaccurate as fuck) HOWEVER!. I get to see pig carcasses get cut to shreds with swords and large explosives, I get to hear David Wenham's* over the top narrations (guy who, if I had the money, would hire to narrate me making breakfast on a morning) and I get to see pretty well choreographed fight scene at the end.
*Credited as Drew Sky. A lot of mystery seems to surround this, no info on Drew Sky on the internet however he sounds the spit of David Wenham. Rumor as it that its a pseudonym, so I'm crediting it to Wenham's voice until then.