In biology and psychology, the Coolidge effect is a phenomenon—seen in nearly every mammalian species in which it has been tested—whereby males (and to a lesser extent females) exhibit continuous sexual activity if they are introduced to new receptive sexual partners, but will eventually stop having sex if the partner has already been copulated with.
Ethologist Frank A. Beach is credited with naming the "Coolidge effect" in 1955, after one of his students suggested the term at a psychology conference. He attributed the neologism to an old joke about Calvin Coolidge when he was President […] The President and Mrs. Coolidge were being shown separately around an experimental government farm. When Mrs. Coolidge came to the chicken yard she noticed that a rooster was mating very frequently. She asked the attendant how often that happened and was told, “Dozens of times each day.” Mrs. Coolidge said, “Tell that to the President when he comes by.” Upon being told, President asked, “Same hen every time?” The reply was, “Oh, no, Mr. President, a different hen every time.” President: “Tell that to Mrs. Coolidge.”