Men in Black1997

Agent K:
All right, kid, here's the deal. At any given time there are around fifteen hundred aliens on the planet, most of them right here in Manhattan. And most of them are decent enough, they're just trying to make a living.

James:
Cab drivers.

Agent K:
No, not as many as you'd think. Humans, for the most part, don't have a clue. They don't want one or need one, either. They're happy. They think they have a good bead on things.

James:
Why the big secret? People are smart. They can handle it.

Agent K:
A person is smart. People are dumb, panicky, dangerous animals and you know it. Fifteen hundred years ago, everybody knew the Earth was the center of the universe. Five hundred years ago, everybody knew the Earth was flat. And fifteen minutes ago, you knew that people were alone on this planet. Imagine what you'll know tomorrow.

James:
What's the catch?

Agent K:
The catch? The catch is you will sever every human contact. Nobody will ever know you exist anywhere...Ever. I'll give you 'til sunrise to think it over. [walks away]

James:
Hey! Is it worth it?

Agent K:
Oh yeah, it's worth it. [pause] If you're strong enough.