Stop Tapping Me!

I'm standing at the register talking to the cashier. Then I feel one of them tapping me from behind. I ignore it and continue talking to the cashier.
It didn't matter that I ignored him- the youngest spoke anyway. I guess the tap was his warning.
"Mama... she passed gas," he said- and it was NOT a whisper.
I just tried to talk louder. I didn't entertain him at all.
So what does he do? He walks around so he can look up to see my face. Make sure I hear him I guess.
My conversation was basically over but she was still ringing me and I did not want her (cashier) to hear any part of what he was saying about his sister, so I quickly started talking again- trying to drown him out, while turning away from him. I'm sure I seemed odd to the cashier now.
"I like those earrings. They look nice on you!" I smiled at her.
She felt her ears.
She hesitated to reply but with a peculiar look she thanked me. She was wearing tiny, small, little earrings. Much like the plain, silver or gold (ball) earrings a child gets when she first gets her ears pierced. Nothing stunning at all.
But it was the only thing I could think of talking about to drown my son out.
Didn't work. He got it in despite my quick thinking.
"She passed gas two times," he said, pinching his nose.
I got my change. Pressed my lips together and felt sweat all over my body.
Even though I did not know the cashier, I was embarrassed.
"Thank you!" I told her. "Come on, let's go!" I told the kids as I headed for the door.
As soon as the door closed behind us I asked him,
"What did you want me to do about it?"
He shrugged his shoulders- realizing I was not happy.
"Did you want me to go all Willy Nilly on your sister or something? I mean there was nothin' I could do but you'd rather broadcast it in the store!"
"I told him not to be a tattle-tell," his sister said, as if she were in the clear.
My attention quickly shifted.
"And you should have used your manners and said excuse me- no, better yet you should not have done that in the store!"
We got in the car and buckled up. Before I could put the car in reverse I felt a tap on my shoulder. I ignored it and threw it in reverse to get out of the parking lot.
Fingers tapping again on my shoulder.
"Mama... who is Willy Nilly?"
I wanted to scream!
"Stop tapping me!"