Challenge us with a non-famous line from a movie

Butch Cassidy and the Sundance Kid

Both correct.

“This is all wrong. I don’t know what it is, but… when I kiss you, it’s almost like I’m kissing… my brother.”

Back to the Future

Yep.

“Low blood sugar, huh?”
“Yeah… it’s a curse.”
“Well, as soon as we get something to eat, you’re walking the rest of the way.”

"I wanted to go bowling!"

“This had better work. We can’t send anyone else up.”

Possibly because it’s one of the most famous often quoted lines in the film. Yet nobody got my entry of “Parading’s better” which is the same character in the same movie.

rubs the back of my neck shyly

I haven’t seen it in more than 10 years, and it’s the only line I could remember. I once bonded with a customer over that line, though.

Some people these days might not fully appreciate the significance of the line.

The actor (Wilfred Brambell) was well known for his role as the father in Steptoe And Son, a popular and long-running sitcom about a father and son who don’t get on well together.

The younger Steptoe frequently called his father “You dirty old man”.

The reference would have been obvious to British audiences at the time, but might be obscure today to British people under 40 and non-Brits of any age.

Steptoe and Son was re-made in America as Sanford And Son.

Thank you. I was too lazy bother mentioning it. Also worth mentioning that when filming AHDN, Grandfather Brambell was in fact 52 years old.

“Well, come down here, hammerhead, and I’ll show it to you!”

“Youth is wasted on the young!”

That is (as best we know) due to George Bernard Shaw. The original-ish quote, from a newspaper interview seems to be "Youth, is the most beautiful thing in this world—and what a pity that it has to be wasted on children!”

Since the terser form became well know later on, there could be dozens of movies that quote it.

The line is exactly as I’ve written it, and I’ve heard it used in just one very famous movie that’s now in the public domain. You’ve probably seen it, since it’s shown on TV every December.

It’s a Wonderful Life?

Bingo! It’s spoken by the grouchy neighbor who tells Jimmy Stewart to stop talking and kiss Donna Reed.

“Don’t look at me, look at the road. That’s how accidents happen.”

Are you sure the Wonderful Life line isn’t “Youth is wasted on the wrong people”?

Don’t think so. Do you have a clip of the movie?

“The wrong people” doesn’t sound as funny.

Yep. YouTube clip (jump to the last few seconds of the video, about 3:45).