Perhaps the most commonly used TV and Movie phrase that I never hear real people use is "just like that.." You hear it in anime all the time and I suppose it's used as a filler for when the original Japanese dialogue is longer than the English. "So you bought a car.. just like that?" "I went to the market and saw Tammy.. just like that!" "Yurimaru wound a line around Benisato's neck when she wasn't looking and killed her... just like that!" I'm still marathoning Babylon 5 and I've heard it like 10 times. This and teenage boys who are somewhat nerdy bobbing their heads when they think they're being cool. I see that all the time too in films and never once have I seen that in real life. Anything you've seen in films like that that that just doesn't jive with real life?
Don't know if you are looking for more subtle actions or speech, but: "Weenie beats up the bully" I have never seen this happen, seen it attempted, but never actually seen it in real life....at least not after 12 years of age.
Or.. Everybody imitating 80's clothing by dressing in their best Pat Benatar outfit. Watch The Breakfast Club or St Elmo's Fire if you want to know how kids dressed. Sure, there were some awful clothes like the red Michael Jackson leather jacket, but they stood out; it wasn't the norm.
