Used to describe someone who has said something really stupid. Can also be used in some occasions when they do something stupid. When used it is said in a long droaning voice and repeated over and over until the person that did something stupid gets really mad at you,possibly resulting in you getting hit.

a guy with the name gerardo known as acting like an idiot and looking like one.

someone who is so stupid that when hearing the term"idiot boy" they reply with "Who are you talking about?" With no clue that even though they are the only other person in the room...well yeah need we say more?