I found myself on Roger Ebert's website reading some of his reviews and stumbled onto his movie glossary. Fans have written about common movie cliches and their observations on common plot archs. I found them entertaining so I've shared a few below, but for more you can visit Roger Ebert's site.
The Encore Rule
In any film that culminates in a concert by the characters, the concert audience will go wild with appreciation, even though the "concert" is only one song long.
The Upper Bunk Rule
Any scene in which two adults are sleeping on a bunk bed will inevitably result in the top bunk collapsing onto the bottom bunk. See: "Black Sheep" and the upcoming "Step Brothers."
Who's Your Daddy?
Whenever a couple very much in love is separated by circumstance and happen to make love the night before they split, they will invariably conceive a child whose paternity will never be obvious to the father once they, inevitably, meet again. (See Keri Russell and Jonathan Rhys Meyers in "August Rush," Robert Redford and Glenn Close in "The Natural," Tom Hanks and Robin Wright in "Forrest Gump," Jim Caviezel and Dagmara Dominczyk in "The Count of Monte Cristo," Linda Hamilton and Michael Biehn in "Terminator," etc.)
The Slap That Ends It All
Near the end of any drama about a troubled romance, the couple will have a heated argument, and the man (who has always considered himself civilized) will lose control and slap the woman's face in a rage. In that second, as the man marvels at the depths to which he's sunk, and the woman ponders what a monster she loved up until a moment ago, they both know it's over.
Name Recognition Rule
The trailer for any movie named after the main character must contain a montage of various characters saying that character's name. See "Alfie," "Charlie Bartlett," "Miss Pettigrew Lives for a Day," "Charlie Wilson's War."
Explosion? What Explosion?
A major character will walk nonchalantly toward the camera and away from a big, napalm-like explosion. Even the Coens use this in "No Country for Old Men." I believe the granddaddy of all such scenes to be the opening stinger in "Goldfinger" in which James Bond is the only person in a nightclub not reacting to a huge explosion nearby, an explosion for which he is responsible.