'Yearning' for quiet life

“Shut your dirty, rotton mouth.”
No, no. I am not telling you buddies. Will I dare? These are the words my Math master used to scream at me when I yawned during his class, which I did repeatedly.
I remember I wanted to say the same words to a Mumbai dentist who sat close to me during treatment, without his mask (those days dentists rarely used one), and let go a wide yawnnnn. I felt a lion was about to pluck my head. (Hope dear dentist friends Nitu and Kavita skip this post)
“Ooof..hehe..I did not sleep properly yesterday,” he rubbed it in.
“Honeymoon?” I wanted to ask, but he had warned that I should keep my mouth wide open and not shut.
Why so much about yawning?
The pretty girl at the mall counter asked me, “You have change?”
“No.”
“Hmmmm,” she opened the cash counter yawning.
“You seem tired?” I said.
She flashed a “what’s your damn problem?” look, banged the counter box and moved to the next customer.
“Can’t you keep your mouth shut?” asked my colleague dragging me.
“You mean dirty, rotton mouth?” I ran with him.