An expression referring to the quote "There's a sucker born every minute." The original quote probably wasn't by P.T. Barnum, but it is commonly attributed to him. It is a valid observation which can be applied to a multitude of everyday situations, but it soon became so overused that it started to sound old and hokey through overuse. Thus, it was reformatted to imply shared cultural literacy on the part of the speaker/hearer.