A character in large room with several other people in it wants to have a private conversation with one, so they walk four steps to the left and talk in a normal tone of voice.
Character's turn the lights off and the room is flooded with blue light so you can still see what is going on.
A character driving a car turns the wheel left and right and regular intervals even though this would only be necessary in some kind of "weave in and out of the orange cones" kind of situation. The actor does this because if he just kept still -- as if he was driving on a basically straight road -- you might think he was doing nothing at all.
An episode will suddenly declare that someone has been doing something for a long time, even though this is the first -- and last -- you will ever hear of it. I am thinking here of the Newsradio episode where Matthew comes in one day and complains that he never has a part in the office discussions about gambling everyone is always having: it is a set up for that episode and that episode alone.
A character has something important to say and announces it but not before being cut off by the person they want to talk to, and being subject to some hugely emotional rant that is the opposite of what they were going to say. When the person finally takes a breath to say "Now what did you want to say," the answer is always something like "Nothing," a claim always taken a face value. The character ranting never notices the emotional state of the person they are talking to. Similarly, a character says something brutally honest and when the reaction is "What?" they claim again "Nothing" and that is the end of that.
There is a long tradition of some kind of "mysterious sex move" that is never revealed but will drive a woman wild.
People having telephone conversations just hang up when the meat of the conversation has been communicated, without saying good-bye.
When characters agree to meet somewhere an address is never needed; phrases like "the coffee shop near your house" do fine.
There are lots more. Help me out.