Idiocracy was a great movie when it was satire, alas it's now at best a documentary (at worst a 'what could have been if things were good' movie) Reality caught up and beat it, alas.
Troll 2. So many quotable lines and unforgettable scenes. And you don't even have to watch Troll 1, because there is no Troll 1 - at least not in relation to, or in the context of, this film.
It's a crime no one has mentioned Neil Breen yet. I just came back from a showing of his latest film at an indie cinema. The whole place was so roudy and screaming at the film. I've never lost my voice watching a movie before 10/10.
Anything directed by Uwe Boll but especially Bloodrayne. It was so bad the actors stopped recording the commentary to get up and go get more wine to finish.
In a very different way to most of the answers on here so far:
A Pigeon Sat on a Branch Reflecting on Existence.
It's simultaneously excruciatingly dull and mindbendingly interesting. A genuinely fascinating film, but requires a huge amount of focus and commitment from the viewer. Possibly my favourite film ever
It's easy to find BAD movies, but for "Best Worst", aka, "So Bad It's Good" category there should be some really redeeming qualities that make it interesting, entertaining, quotable, or just plain fun.
Tank Girl is a mess, with Ice (I'll do anything to be a movie star and get out of rap) T as a kangaroo-guy, early Naomi Watts as eye candy Jet Girl and smart-aleck Lori Petty leading the pack as Tank Girl. Weird as all hell but some absolutely hilarious dialog ("I had a swell time, but the swelling's gone down..") and it's fun to catch those building their acting careers - not just Ice T and Naomi, but Doug Jones, Iggy Pop, James Hong, Richard Schiff, etc..
Frankenhooker is possibly the better film but super-tongue-in-cheek fun, loaded with with it's-so-dumb-snort! dialog like "Errrrkkk! Hey - Wanna date?" and "Oh, God...She's gonna blow! Duck and cover!", of course plenty of 1980s bewbs for the less-discerning amongst us.
Both highly recommended...in fact, the higher you are, the better they are. ;)
Transformers: Dark of the Moon, I love this movie for some reason. I actually enjoy Shia in this role, the action/ special effects are great, and the score from Steve Jablonsky is one of the best I've heard in a blockbuster (yeah I said it). Great voice acting as well with Leanord Nimoy joining in. It also felt like a true ending to a trilogy.
Slipstream (1989).. check it out if you haven't seen it. Mark Hamill, Bill Paxton and produced by Gary Kurtz (Star Wars, ESB, American Graffiti, The Dark Crystal).. This was released 5 years after Return of the Jedi with that star power and didn't even get a US cinema release.
You got to watch All Star Superman on HBO Max. It is honestly the most insane and stupid superhero thing ever made and every moment is more crazy than the last. It is a 10 out of 10 laugh riot while high. I want to give some examples but I also don't want to spoil this for anyone who hasn't seen it.
The English dub of the kung fu movie Shaolin V. Ninja. Voices are wildly inconsistent, plot makes no sense. A great time. Pretty sure it’s on YouTube. At least it was some years ago.
The directors made a bunch of movies using the same technique: buy footage from unfinished Asian action movies. Splice them with footage of European martial artists sparring in the most bizarrely colourful outfits and Ninja! headbands. Dub in ridiculous dialogue about a vague revenge plot.
Don't play any drinking games with this movie. You'll die of alcohol poisoning before the third act.