"Sometimes, it just means, 'forget about it.'"

The Movie: Donnie Brasco, 1997 (Paul Attansio, screenwriter, from the book by Joseph D. Pistone and Richard Woodley; Mike Newell, dir.)
Who says it: Johnny Depp as Joe Pistone/Donnie Brasco, an FBI agent who goes undercover to join the Mafia
The context: Joe is explaining all the different uses for the phrase “forget about it,” to an FBI technician, echoing something his Mob mentor (Al Pacino) told him.
How to use it: To remind yourself that sometimes there is no hidden meaning.

I looked at my schedule for the week and thought, "Oh my gosh, it's my last week here!" And then I laughed. But one way or another it is my last week here. If the car dies again, it's late enough in the season that I can now fly with Dizzy, and I'll just sell that dang Blueberrymobile. We'll assume that won't be necessary.

Of course, none of my friends believe I'm leaving any more, either. The other night we were talking about where we'd gather to watch the second and third Presidential debates. Maeve said, "I won't be here for the second one," and I said, "I won't be here for the third one." Everyone just looked at me blankly for a minute... and then they laughed.

The most ridiculous thing is that I shipped all my cool-weather clothes to Maine already, thinking I wouldn't need them before I arrived. If I wind up having to buy new sweaters before I even leave, I'll be annoyed.