I use it when we all need a smile.
Sometimes a child will try to get me engaged in a power struggle where I have given directions, the members of the class are all following and he/she is waiting, not following. Some students may have, on their own not wanting me to have to talk about GUFF, put their hands up and said, "Stop that"! to him/her. Yet he/she is wanting a power struggle. This little laugh can get him/her back on track and following directions.
At other times it helps students to give all of their attention to me. After a class-yes, we do a ha-ha-ha similar to hands and eyes. I do not know if I am really following a Whole Brain Teaching way of using this. I have not been trained, but I have watched all of videos online and read everything that I could find online. I thought about flying to a seminar, however I have not been able to yet.