Geronimo!

Two men jump out of a plane. According to instructions, they pull the yellow cord, which should open up their parachutes. It works indeed for one of them.

The other parachute doesn't do what it's made for, and the man tied to it cries: "My parachute wont't open! MY PARACHUTE WON'T OPEN!"

Says the other guy: "Stop yelling. No one will blame you, it's just an exercise."