"I've never seen purple underwear before"

"I figured...hey, couldn't hurt."

"Papa do you think we can get away this"
"Honestly no. Dishonestly we've got a shot."

I'm not sure I'm doing it right....

"Last night, Darth Vader came down from planet Vulcan and told me that if I didn't take Lorraine out that he'd melt my brain."

"The way I see it, if you're gonna build a time machine into a car, why not do it with some style?"

"If my calculations are correct, when this baby hits eighty-eight miles per hour... you're gonna see some serious shit."

"What about all that talk about screwing up future events, the space-time continuum?"

"Well, I figured, what the hell."

"Hey butthead!"

"You're not thinking fourth dimensionally!"

"I'm sure that in 1985 plutonium is available in every corner drug store, but in 1955 it's a little hard to come by!"

"This one's an oldie, but... ...Well, it's an oldie where I'm from."

"Your name. It's Calvin Klein, isn't it? That's what it said on your underwear...?"

It's make like a tree and LEAVE! You sound like an idiot when you say it like that!

Dr. Emmett Brown: [Marty is showing Doc Brown the 'flux capacitor' in the DeLorean time vehicle] It works. It works!
[grabs Marty]
Dr. Emmett Brown: I finally invent something that works!
Marty McFly: [quietly] You bet your ass it works.