I have an "all-star" trio sorts when it comes to this question.
I.
The Room - I am not going to say a thing about it. Go watch it. Have fun.
II.
The Cat in the Hat (2003) - I consider this movie
The Room of "children's movies." The sheer fun of this movie lied in its extremely odd focus on adult humor that allows the movie to both distract from what the source material is all about and be an extremely bizarre cavalcade of comedy.
III.
Gods of Egypt - This movie strangely stands the test of time as while it is an otherwise very basic and perhaps very cliched adventure movie, it contains a glorious combination of hokey acting and very noticeable CGI effects that give this movie shelf life. Gerard Butler is perhaps the only actor whose performance doesn't come off as phoned in as if he is trying to save the movie. I laughed almost a good ten minutes straight at one point watching this movie. It deserves, in a few respects, the "so-bad-it's-good" moniker.