Have you ever had a laughter attack?
Laughed like a lunatic for absolutely no reason? And then, when you are in that mode, everything, every single little thing which is so ordinary seems really funny and you just can't stop laughing. It is a bit like being drunk, expect that you are completely sober and in your senses, but your rib has gone into auto-tickling mode, just like a computer that has hung. You convulse helplessly with laughter, tears streaming down your face, clutching your sides and still laughing, even though your tummy hurts...