Monkey see, monkey do" is a traditional clich�. A clich� (from French, stereotype) is a phrase or expression, or the idea expressed by it, that has been overused to the point of losing its intended force or novelty, especially where the same expression was at one time distinctively forceful or novel. This particular cliche' popped up in America in the 1920's. The American version of this saying often refers to a child's urinating process. The child observes another's urination and then imitates it.
The European version is slightly different, In the UK, "Monkey see, Monkey do", refers to to the learning process without understanding why or how it works. (Source: Wikipedia)