The one that pisses me off the most is "the misunderstanding." It started out in romantic comedies, and it's been moving more and more into other genres. To create conflict and drama, the main character and the love interest have a misunderstanding, which leads to a fight, which leads to them splitting up, which leads to some sad music accompanying a montage of their happy time, and one of them figures out the misunderstanding, and they get back together.

Usually, the whole thing could've been prevented if they weren't both morons, and at this point, it's gotten to be so formulaic that it no longer adds any tension. We know they're going to get back together; why bother?

I remembered one earlier today.

The "Fish Out Of Water" scenario.

You know, the family or person from the city winds up in the country and does not fit in. Or vice versa.... Then they figure things out and everyone is happy at the end.

Twist

Wedding Crashers and I Love You Man are two great examples of this, even though it is with a pair of friends.

Thought of a new one today.

A character or characters are complete idiots, or have no talent in anything whatsoever but due to incredible misconceptions is thought to be incredibly smart or very dangerous.

Beavis and Butt-Head Do America!

Ha ha, yes!


I thought of some more:

The ugly girl gets the cute guy...except the ugly girl isn't actually ugly. (Where they throw on a pair of glasses and some braces, and call the girl ugly).

The girl gets the guy even though they're not compatible...except they actually are compatible. (basically the same as the ugly girl one).

Everyone's straight in kids movies. (heterosexual relationships are often portrayed in kids movies, though usually only romantically, but homosexual relationships never are.) This is especially true in Disney movies.
(This one kind of pisses me off, because there's no logical explanation for it.)

Everything conveniently falls in place. (events that are extremely improbably just happen to happen to drive the plot of the movie.)

Oh, another one is where something bad happens and they immediately jump to the conclusion that the child is responsible, and berate them for it. (Hide & Seek and Don't Be Afraid of the Dark are two examples, but I'm sure there are more)