So help me god, if you say Plan 9 from Outer Space (1957) I'm gonna smack you hard enough that you fly right out of this thread and beyond the stratosphere, definitely not with weak little kiddie gloves like with Will Smith and Chris Rock.
In your opinion, what is the best intentionally crappy B-Level movie of all time? By that I mean a movie with a director, producers, and actors that are totally self-aware that it is ridiculous and deliberately aimed at making you laugh at the charm of its awkward nature or poor quality. That would immediately disqualify cult classics like The Room (2003), since its kooky director Tommy Wiseau was apparently totally serious in his approach. There are some major productions that turn into box office bombs that certainly evoke the same feelings, such as Dan Aykroyd's Nothing but Trouble (1991). As a Warner Bros film that had a $40 million budget in the early 1990s, one could argue it is not exactly a B-Level film, but it at least borders on that territory and definitely has that B-Level campiness appeal:
Barring that, here are some legit notable candidates in chronological order (but by no means is this an exhaustive list, please add your own suggestions):
The Toxic Avenger (1984)
They Live (1988):
Frankenhooker (1990):
The Dark Backward (1991):
Kung Pow! Enter the Fist (2002):
Machete Kills (2013):
Return to Nuke 'Em High (2014):