This is Hidden Brain, I'm Shankar Vedantam.

It's summer time, so we felt we had to start our show with a scene from the iconic summer vacation movie.

Where in the 1980s, the Griswals are packed into their station wagon.

It's pouring rain. Everything has gone wrong.

They're on this disastrous road trip to a most centric theme park.

The wife and kids suggest that it's perhaps time to just go home.

I don't want to be in the car anymore. I want to go home!

Clark, under the circumstances, I wouldn't mind if we just went home.

But the dad, Chevy Chase, has other ideas.

We're 10 hours from the fun park and you want to bail out.

Well, I'll tell you something, this is no longer a vacation.

It's a quest. It's a quest for fun.

I'm going to have fun and you're going to have fun.

We're all going to have so much f***ing fun when we need plastic surgery to remove our goddamn spiles.

I got to be crazy. I'm going to pilgrimage to see a moose.

Praise Mardi Mouss!

Summer vacations. We wait for them all year.

We pour time, energy and money into planning them.

Expectations run unreasonably high.

Coming up, a summer edition of Stopwatch Science.

How to plan a vacation? What vacations can reveal about your stock portfolio?

And why vacations can be bad for your waistline?

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