The soup analogy is,
You only need a single spoon to sample the soup, provided it is well stirred.
It has been used several times here Sampling distributions of sample means and What is your favorite layman's explanation for a difficult statistical concept?. It is also referenced on other websites, for example Soup analogy. It has a corollary that "if the soup is not well stirred, a single spoonful may not be representative."
What is the origin of this aphorism? The linked answer above finds in in Behar, R., Grima, P., & Marco-Almagro, L. (2012). Twenty Five Analogies for Explaining Statistical Concepts. The American Statistician But that paper surely isn't the origin of the saying. I remember it from a university lecture in the 1990s, and even then it was treated as a proverbial saying. Who first said this, and roughly when? What was the original quote?