phone calls

One thing about TV that immediately pulls me out of suspended disbelief is when characters on TV shows don't say 'bye' when on the phone. They usually just hang up after a witty retort. Now maybe in other parts of the US, people just hang up when they're done talking, but I've never encountered this behavior.

Why don't TV characters ever say "Goodbye!" or 'thanks!' -- it's always an abrupt ending to the conversation.