Joke:What is a joke?
One day at a busy airport, the passengers on a commercial airliner are all sitting down, waiting for the cockpit crew to show up so they can get under way. The pilot and co-pilot finally appear at the back of the plane, and begin walking up to the cockpit using the centre aisle. Both seem to be completely blind. The pilot is using a white cane, bumping into passengers left and right as he stumbles down the aisle, and the co-pilot is using a guide dog. Both are wearing huge sunglasses to cover their eyes. At first the passengers do not react; thinking that it must be some sort of practical joke.
After a few minutes the engines start and the aeroplane starts moving down the runway. The passengers look at each other with some uneasiness. They start whispering among themselves and desperately look to the stewardesses for reassurance. Then, the aeroplane starts accelerating rapidly and the passengers begin panicking. Some passengers are praying, and as the plane gets closer and closer to the end of the runway, the voices are becoming more and more hysterical. When the aeroplane has less than 20 feet of runway left, there is a sudden change in the pitch of the shouts as everyone screams all at once.
At the very last moment the aeroplane lifts off safely. In the cockpit, the co-pilot breathes a sigh of relief and tells the pilot: "You know, one of these days the passengers aren't going to scream, and we're all going to get killed!"