In comedy, a dick joke, penis joke, or (in British slang) a knob joke is a joke that makes either an indirect or a direct reference to a human penis, also less commonly used as an umbrella term for dirty jokes. The famous quote from Mae West, "Is that a gun in your pocket or are you just happy to see me?" is cited as an example of a penis joke. Attitudes towards dick jokes vary.
The impact of this kind of joke, as with most humor, rests with the unspoken connotation, specifically in this joke set in a class in medical school:[1]
"A professor gives his physiology class a spot quiz. One question he asks is, "What part of the human anatomy expands to ten times its normal size during periods of intense emotion and excitement?" He picks a rather overdressed girl in the front row to answer it. "Miss Callahan!" The indicated girl, who heard the question, stammers with some embarrassment: "Professor, I'd rather not answer that question." The professor says, "That's all right, Miss Callahan, you don't need to answer it. Is there anyone present who can answer it?" He notes an interested face in the back of the classroom. "Mr. Hawkins!" Hawkins says, "Yes, Professor, it is the pupil of the eye that expands to ten times its normal size during periods of emotion and excitement." The professor says, "That is correct, Mr. Hawkins." Then he turns to Miss Callahan. He says, "Young lady, two things are obvious from your reaction to this question. One, you haven't studied this week's assignment; and Two, I'm afraid marriage is going to be a tremendous disappointment to you."