@Iago  
In fact, the entire reason the DeLorean in the movie was for that single scene. The gull-wing door on the car and the stainless steel body, combined with the radiation suit, made the family believe Marty was an alien from outer space who had crashed into their barn. Old Man Peabody ran for his shotgun instead of asking questions.
 
And unfortunately, Marty wasn’t really aware that he was in 1955.

@Blissey1  

 
He didn’t do it deliberately. He crashed there after the time jump and had the mask of the radiation suit fall on his face. The family thought that he was an alien invader and the father attacked him with a shotgun, so he was forced to flee, rather than try to explain himself.

@Vitruvius  
uh no, I remember the overall plot fo the movie jsut fine. I jsut don’t remember why he had to go and scare the living daylights out of that family on the farm

@Vitruvius  
Actually it’s because Lorraine’s dad hit George with his car (after he fell out of the tree) leading to Lorraine to develop florence nightingale syndrome for George.
 
But when Marty sees this happened he knee jerks and pushes his dad out of the way thus screwing up the timeline.

@Background Pony #D480  
It comes up early on, before Marty goes back in time. They’re all aware that George McFly met Lorraine (in the original timeline) when he fell out of a tree, and the story gets told again. Marty thinks to ask, “What were you doing in that tree, anyway?” He doesn’t get an answer until he sees for himself in 1955.

@Vitruvius  
Makes you wonder if she ever found out about it. would have been one hell of an interesting conversation.

@Darth Prime  
Well, yes. By “admiring” I mean “spying” and “from afar” I mean “from across the street, hiding up a tree.”

@Vitruvius  
>Admired her from afar
 
I.E. he was a peeping tom.

@Blissey1  
Marty’s arrival in 1955 prevented his mother from meeting his father, who admired her from afar but lacked the confidence to do anything about it. Marty used his teenage father’s enthusiasm for science fiction (and his own knowledge of sci-fi that didn’t exist yet) to coerce his father into asking his mother to a dance.
 
And it wasn’t actually a Darth Vader mask he was wearing - it was the radiation suit required to operate the time machine, which in the first movie was powered by plutonium.

@Eeveeinheat  
it’s when he first arrives in the past and crashes into the barn. He puts on a darth vader mask and uses this line to scare the family into letting him do… something
 
gawd it’s been a while since I’ve watched that movie.

@Blissey1  
Huh. I do not remember this scene from Back to The Future at all. I even looked it up on YouTube and the memory escapes me. No recollection whatsoever.

@Eeveeinheat  
but this is a movie quote

@Darth Prime  
And the planet Vulcan, apparently. That really makes me wonder if George McFly sued George Lucas and Gene Roddenberry over those.

You should have said asteroid. Would have made the wrongness complete.

@Darth Prime  
 
Of course, time paradoxes can do that to you.

So hang on. George McFly became a successful sci-fi novelist writing stories based on that encounter meaning he “created” Darth Vader before George Lucas.

So… she needs to get her parents together before the conveniently slow grandfather paradox ushers her out of existence?

Don’t melt my brain!