Engineer Joke 
Scene: public executions by guillotine 

First condemned person steps up, a minister. 
Switch is pulled. Blade doesn't come down. 
Minister cries out: "God knows I am innocent!" 
He's pardonned. 

Second condemned person is a revolutionary agitator. 
Switch is pulled. Blade doesn't come down. 
Guy cries out: "The revolution cannot be stopped!" 
He's pardonned. 

Third condemned is an engineer. Same deal. 
He looks up, points up, says, 
"I think your problem is that the cable is binding right here..."