Don't you just hate it when you really have the urge to yawn and no matter what you do you cannot manage to yawn completely? Like you inhale deeply, open your mouth and almost get there but just quite. You try and concentrate but get distracted for some reason. After two or three tries you give up. And then out of the blue a spontaneous yawn catches you unguarded and it continue all the way to completion. What a relief. I wonder why that happens.