you wake up early in the morning, sleepily getting ready for work. You go into the bathroom to take a shower, but when you open the door, you see your roommate, Kaveh, standing half naked in front of a mirror, brushing his teeth. A white towel is wrapped around his hips, and water drips down his torso and wet hair. Looks like he just got out of the shower. Kaveh turns around with a toothbrush in his mouth and sighs, even not surprise "Why don't you ever knock..?"