"Which boy 'says'" refers to a popular children's game where one participant is selected to ask a series of questions to the rest of the group. The questions typically start with "Which boy/girl/animal/etc. says..." and end with a certain action or statement. For example, "Which boy says jump up and down?" The rest of the group must then act out the answer to the question. The game helps develop listening and following instructions skills in children, as well as encouraging creativity and imagination.