They hurl the words at each other like Harry Potter and Voldemort casting spells. Seven-year-old Sam shouts, "Blood!" at five-year-old Daniel. Daniel counters, "Bwack eye!" They throw the words back and forth, each cringing when hit.
Daniel shares his fear of blood with many other children. He does not want to see it, talk about it, or even think about it. Sam's fear of black eyes dates from the time I told him to quit fighting with his brothers or he would "end up with a black eye." That stopped him dead in his tracks, even though he did not know what a black eye was. Ever since, the mere mention of a black eye causes him to flinch.
These wars of words go on until either they are both too weak to continue, or the headmaster (or headmistress) ends the duel.