Afterwards, the two men walk drunk out of the bar and run into two prostitutes, a blonde and a brunette. “Hey!” say the prostitutes. “Wanna have a good time?”
“I would!” says the sergeant. “Me too!” says the corporal.
“Are you sure about that?” the sergeant asks again. “Of course I’m sure!” replies the corporal. “I am no longer a private. I am a corporal now!” So the sergeant takes the blonde and the corporal takes the brunette.
“I must warn you,” says the brunette, “I have the clap.” Neither of the two soldiers know what “the clap” is, so the sergeant looks it up in his pocket dictionary. “It’s safe,” he tells the corporal.
A week later, the sergeant visits the corporal in the hospital. “Why did you tell me it was safe?” asks the corporal.
“The dictionary told me the clap only affects the privates,” replies the sergeant, “and you are a corporal now.”