My wife and I love a certain type of terrible movie. We love movies that are so bad they're good. The best example of this is The Room. Holy shit that thing is glorious.
I personally believe that one thing enjoyable so bad they're good movies have in common is that they were not meant to be bad. Movies like Sharknado do not fit into this category because it was made bad on purpose. The reason The Room is the king of SBTG movies is because the man who made it was really trying to make a good movie.
Here are some of my favorite SBTG movies to sit around and watch with a group of friends, alcohol and or pot are highly recommended accessories.
The Room
Mac and Me
Howard the Duck
Plan 9 From Outer Space
Night Killer
Silent Night Deadly Night part 2