You MUST be Tired

My mother is always saying to me in her tone, "Would you quit yawning you look like a fool!" So yesterday while in the clinic my mother yawned with a big "AHHHH".A very old man stopped DEAD in his tracks looks at my mom and says, "BOY someone is tired." Who looks like the fool now?
http://www.youtube.com/watch?v=iABi1M8BZTg