I remember when I was a kid, I didn't get humor in movies that make fun of other movies. I took them all seriously. When I first saw Mafia, I totally kept questioning it and kept asking how was it possible like how did the teenage boy swim across the ocean, how is that possible? How did it fit up the donkey's ass (whatever animal they used) and how did he survive in there, how is that possible? How on earth did this little boy have all this stuff in his shorts such as a shovel? As he kept running away from the guys everything fell out of his shorts creating an obsticle course for the men, how can those dinosaurs still be alive to kill Chucky, etc.
My brothers had to keep telling me "it's a joke"
When I saw Scary Movie when I was 15, I also kept questioning it like how can Drew get hit by the car and not be hurt, How can Gail shoot the high school student in front of everyone and they all act like it was okay thing to do because there was no panic and no police came and arrested Gail for the murder of a high school student but it wasn't okay for someone to go and kill Drew, when a girl is being attacked by the killer from her car, how can Gail just stand there and watch and not do anything about it, etc.
My brothers also told me "It's a joke" "it's not meant to make any sense" "They're just making fun of other scary movies, it's not meant to be real" etc.
Now I don't get confused by those movies anymore because I understand they are just parodies, they're not supposed to be plausible, realistic, they're supposed to be dumb because that's what makes it funny.
Other movies I know that are like that, Not Another Teen Movie, Date Movie, and of course Spy Hard even though it wasn't as dumb as the others. And I think the Naked Gun movies are like that too.