Back to the Future1985

Lorraine:
Marty, why are you so nervous?

Marty:
Lorraine, have you ever, uh, been in a situation where you knew you had to act a certain way, but when you got there, you didn't know if you could go through with it?

Lorraine:
You mean, like how you're supposed to act on a first date?

Marty:
Well, sort of.

Lorraine:
Oh, I, I think I know exactly what you mean.

Marty:
Y-y-you do?

Lorraine:
You know what I do in those situations?

Marty:
What?

Lorraine:
I don't worry. [kisses him hard, then stops and pulls back to see Marty is shocked] This is all wrong. I don't know what it is, but when I kiss you, it's like I'm kissing... my brother. I guess that doesn't make any sense, does it?

Marty:
Believe me, it makes perfect sense.