The social rules that apply in real life do not apply exactly the same in fiction as portrayed on either TV or in movies, nor do the social rules that do apply TV and movies apply exactly the same in real life. There is a relationship there, but it is not 1 to 1. This is pretty obvious when it comes to comedy. Take this snl sketch for example.
This sketch is funny to the viewing audience precisely because it is not funny to the fictional characters portrayed. If you imagine the sketch being preformed differently, where Chris Farley is clearly being sarcastic in his rage, and everyone around him is having a good time watching the performance, then you'll see that if it was done that way it would not be that funny to the viewing audience. And, of course, if you were actually in a restaurant and unruly customer both savagely beat, and was savagely beaten by the staff, you (hopefully) would not look on with belly laughs. If on the other hand you were actually at that restaurant, at Chris Farley's table, and you saw him reach with feinted anger, you probably would be amused.
In both amusing cases (fainted anger in real life and real anger in a sketch) what is funny is a horrible act that is one step removed from reality. In real life it's removed by sarcasm, and in the sketch is removed by fiction. If you remove it by two steps (an actor pretending to pretend to be angry), it's not funny, and if it's completely real, its also not funny. Of course there is more going on than just something horrible being one step removed from reality (Schindler's List is not a comedy), but you get the point.
What made me think of this was Keoni Galt's link to Why I stopped Watching “The Big Bang Theory” AndWhy You Should Too. And although I certainly agree with Galt's main point about the problems with the underlying narratives as they relate to how men and women are supposed to interact, I just don't have a problem things like actors being rude and inconsiderate. In practice I don't think that
If you watch Sheldon too much, you will find yourself (either outloud or in your inner monologue) correcting people for the most inane things.
is any more true than watching Chris Farley in the following will start making me yell “You stupid bitch” at women I hardly know on a regular basis.
Not all of the one off relationships are so simple though. Some can be quite subtle and hard to recognize. So anything you see on TV, take with a grain of salt. For example many actions that are seen as being sweeping romantic gestures on film, would be off puttingly desperate in real life.