Telegram from my Arse

A young boy was out shopping with his mother in the local supermarket. While walking along one of the aisles the young boy let rip with the loudest fart he could muster.

"I beg your pardon!" said his mother "Was that you who did that?"

"Yep." replied the boy, grinning "It's a telegram from my arse to let you know there's a shit on its way."