Back to the Future 101
Back to the Future (1985). Marty McFly is your average, slacker teenager, who is friendly with a wacky inventor named Doc Brown. When Doc creates a time machine out of a DeLorean car, Marty is accidentally transported into the year 1955. There, he stumbles upon a younger version of his parents and accidentally disrupts their meeting. He must get the two together so that they will get married - or else he won't exist!

Back to the Future Part II (1989). Picking up where the first movie left off, Doc Brown and Marty go into the future to help Marty's future offspring. After doing that they return to their own time, only to discover that things have changed for the worse. While in the future, Marty bought a sports book so that he could know the results of sports events and make money by betting on them. Doc Brown nixed Marty's plans, but they learn that bully Biff Tannen overheard their conversation, got the book, snuck into the time machine, went back into the past and gave the book to himself. Now, Biff has not only amassed a fortune but is also extremely powerful. So Doc and Marty must go back to when the past Biff received the book - in 1955 on the night of the dance - and get it away from him.

Back to the Future Part III (1990). The conclusion of the trilogy sends Marty McFly on a rescue mission to the year 1885, where he must save Doc Brown from death at the hands of yet another member of the Tannen clan. However, a number of complications prevent a quick return to the future: a lack of gasoline for the time-traveling DeLorean, a band of gunslinging outlaws, and a schoolmarm with affections for the smitten Doc.

Why am I a Back to the Future fan?
Romance. Adventure. History. Destiny. What's not to love?

Mr. Strickland: You don't have a chance, you're too much like your old man. No McFly ever amounted to anything in the history of Hill Valley.
Marty: Yeah, well, history is gonna change.

Marty: Wait a minute, Doc. Ah... Are you telling me you built a time machine... out of a DeLorean?
Doc: The way I see it, if you're gonna build a time machine into a car, why not do it with some style?

Marty: Plutonium... wait, are you telling me that this sucker is nuclear?
Doc: No no no, this sucker's electrical, but it requires a nuclear reaction to generate the 1.21 gigawatts of electricity I need.
Marty: Doc, you don't just walk into a store and buy plutonium-- did you rip that off?
Doc: Shhhhhh. Of course. From a group of Libyan nationalists. They wanted me to build them a bomb, so I took their plutonium and in turn, gave them a shiny bomb-casing filled with used pinball machine parts.

George McFly: Lorraine, my density has bought me to you.
Lorraine Baines: What?
George McFly: Oh, what I meant to say was...
Lorraine Baines: Wait a minute, don't I know you from somewhere?
George McFly: Yes. Yes. I'm George, George McFly. I'm your density. I mean... your destiny.

[1955 Doc is watching a video of 1985 Doc]
Doc: What on Earth's this thing I'm wearing?
Marty: Ah, this, this is a radiation suit.
Doc: Radiation suit? Of course, because of all the fallout from the atomic wars.

Marty: Calvin? Wh... Why do you keep calling me Calvin?
Lorraine Baines: Well, that is your name, isn't it? Calvin Klein? It's written all over your underwear.

Doc: Then tell me, Future Boy, who is President in the United States in 1985?
Marty: Ronald Reagan.
Doc: Ronald Reagan? The actor? Who's Vice President? Jerry Lewis?

Doc: If they don't meet, they won't fall in love, they won't get married and they won't have kids. That's why your older brother's disappearing from that photograph. Your sister will follow, and unless you repair the damage, you'll be next.
Marty: Sounds pretty heavy.
Doc: Weight has nothing to do with it.

Marty: Whoa, this is heavy.
Doc: There's that word again, "heavy". Why are things so heavy in the future? Is there a problem with the earth's gravitational pull?

Doc: I'm sure in 1985, plutonium is available at every corner drugstore, but in 1955 it's a little hard to come by.

[Flying above Biff in 1955]
Marty: There he is, Doc! Let's land on him, we'll cripple his car.
Doc: Marty, he's in a '46 Ford, we're in a DeLorean. He'd rip through us like we were tin foil.

[In the year 2015]
Doc: The justice system works swiftly in the future now that they've abolished all lawyers.

Biff Tannen: That's about as funny as a screen door on a battleship.
Marty (under his breath): It's "screen door on a submarine," you dork.

Doc: The time-traveling is just too dangerous. Better that I devote myself to study the other great mystery of the universe: women!

Marty: That's right, Doc. November 12, 1955.
Doc: Unbelievable, that old Biff could have chosen that particular date. It could mean that, that point in time inherently contains some sort of cosmic significance. Almost as if it were the junction point for the entire space-time continuum. On the other hand, it could just be an amazing coincidence.

Doc: However, the destruction may be very localized, limited to merely our own galaxy.
Marty: Well, that's a relief.

Marty: Is there a back way out of here?
Bartender: Sure.
Marty: Where is it?
Bartender: Out the back.

Doc: Reach!
Engineer: Is this a holdup?
Doc: It's a science experiment!

Doc: Clara was one in a million. One in a billion. One in a googolplex!

Buford "Mad Dog" Tannen: What's your name, dude?
Marty: Uh, Mar-, uh... Eastwood. Clint Eastwood.
Buford "Mad Dog" Tannen: What kind of stupid name is that?

Buford "Mad Dog" Tannen: If you don't show, I'll hunt you and shoot you down like a duck.
Gang Member: It's "dog," Buford. Shoot him down like a dog.

Buford "Mad Dog" Tannen: You owe me money, blacksmith.
Doc: How do you figure?
Buford "Mad Dog" Tannen: My horse threw a shoe. Now seeing as you're the one who done the shoe, that makes you responsible.
Doc: Well, since you never paid me for that job, I'd say that makes us even!

Doc: Marty, you're going to have to do something about those clothes. You walk around town dressed like that, you're liable to get shot.
Marty: Or hanged.
Doc: What idiot dressed you in that outfit?
Marty: You did.

Doc: Marty, it's perfect! You're just not thinking fourth dimensionally!
Marty: Right, right. I have a real problem with that.

* Accidents can produce some great ideas.
* No man should know too much about his own destiny.
* There's nothing wrong with calling a boy.
* Nice girls get angry when guys take advantage of them.
* One rejection isn't the end of the world.
* The past affects the future.
* It's important to do things with style.
* Parents are people too.
* Be very suspicious if a teenage boy tells you he was bird-watching.
* When all else fails, blame men from outer space.
* Choose your band's name carefully.
* Don't be bullied into doing things.
* Don't be a bully. It's hard on your car.
* Names really can't hurt you.
* Never marry solely for money.
* Be prepared to run when asking nosy questions.
* Once a slacker does not mean always a slacker.
* If you put your mind to it, you can accomplish anything.
* Stand tall and have some respect for yourself.
* One small event can change the world.
* Your future is whatever you make it.

In 1955, Doc and Marty are at the high school, looking for his (future) father. They find him being picked on by the local bullies; Doc turns to Marty and optimistically suggests that he was adopted. (From the first movie.)

In 2015, Marty is on the sidewalk in front of the movie theatre. Suddenly, from an advertisement for Jaws 17 (or something) a large holographic shark appears and reaches forward, engulfing Marty in a bite before it harmlessly disappears. Marty screams, but when the shark is gone, Marty grumbles that it still looks fake. (From the second movie.)