Speaking about cliche plot devices in the last post, most films and TV shows today are greatly lacking in originality. As a film buff myself, there are a couple of times where the only motivation in sitting through a really bad movie/TV show is to predict what will happen next.
There some famous cliche stuff that people have already covered, such as Roger Ebert's Principle of Evil Marksmanship and the One-at-a-time Attack Rule. So I'll give my own observations:
The In Sync Bad Weather Rule
This rule comes into play whenever there is a scene where the character in question undergoes a great emotional trauma after (1) finding out his/her lover has been cheating on him/her, (2) having a massive argument with his/her family which he/she vowed never to return home again (3) receiving news that his/her lover/best friend/family member has died having met a horrific accident (4) any bad news stemming from love, friendship or family issues that happened at night. After this rule is triggered the weather will changed into a heavy downpour (complete with lighting and thunder). The character at this point will not be seeking shelter but instead run aimlessly in the open and getting drenched.
Examples: Almost every film, TV show and Channel 8 dramas (where the uncompromising dad is always played by Chen Shu Chen)
Principle of the Formidable Last Bullet
In an action flick towards the climax where the main boss is either (1) getting away or (2) in a final duel with the hero, the hero's final bullet will be exceptionally accurate and deadly. In the case of the former scenario where the villain is nearly disappearing out of view the hero will still be able to pick him off with his final bullet in spite using his non-shooting hand (due to an injury to his shooting arm) and the sheer amount of distance between them. In the case of the latter where the villain (usually equipped with a seemingly indestructible body) is winning, this bullet fired by the hero will locate the one milli-centimeter chink in the villain's armour, killing him.
Point to note: However this principle can be overruled by the I'll Be Back Rule, in which the villain is planned for the sequel.
Examples: LXG, Die Hard 3, John Woo Hong Kong action flicks
More to come.