Who said "I gotta say, for a mad scientist, you're not so bad."?

This quote is attributed to Marty McFly.

I gotta say, for a mad scientist, you're not so bad. - Marty McFly

"I gotta say, for a mad scientist, you're not so bad."

Marty McFly Friendship

"This is heavy."

"There's that word again, 'heavy.' Is there something wrong with the Earth's gravitational pull?"

"I'm your density. I mean, your destiny."

"You're my best friend, and I care about you, but don't ask me to do this."

"Friendship is built on trust and honesty."

"True friendship is worth more than gold."

"Good friends are like stars, always there even when you can't see them."

"Friendship means sacrifice."