First Lady story, and how it came to deal with male sexual promiscuity:
In the 1920s, then-President Calvin Coolidge and his wife Grace were visiting a chicken farm. They were taken on separate tours, and while Mrs. Coolidge was being shown a chicken pen, she was informed that their roosters could mate many times a day. "Be sure to tell that to Mr. Coolidge when he gets here," she replied.
When the President was subsequently told this fact, he asked "With the same hen?" "Oh, no, Mr. President, with many different hens in a row," was the answer.
"Well, tell THAT to Mrs. Coolidge," responded the President.
From this story has come the term "Coolidge Effect" for the observation that human males will have sex more frequently if presented with a succession of different females, than the lesser number of times they will have sex with the same female in an identical time period. This has fueled speculation about whether men are inherently able to be faithful to one woman (or perhaps man in the case of gays), or if sexual promiscuity is the more natural human male behavior.