Some of these pictures and descriptions may give away plot details that you might not want to know before watching the film.
"The story of a rebel and his bike."
When Pee Wee finds a pet shop on fire he runs in to save all the animals. He sees a terrarium full of garter snakes and gives it a disgusted look each time he passes it to grab another animal because he's terrified of snakes. Finally, screaming, he runs out of the store with his hands full of snakes then faints, falling to the ground, letting all the snakes crawl away.
The snakes used were all real live garter snakes. Paul Reubens is to be commended for his courage in handling these completely harmless creatures.
(Maybe he was just disgusted by the foul smell they can make. I wouldn't blame him for that.)