What does smh mèan? should i know that?

* shaking my head *

http://www.urbandictionary.com/define.php?term=smh

Sniff my hooves.

People had said it means "smacks my head" and "shaking my head". So basically it is a form of showing disapointment.

it means shrug my head. An easy way to find out what abbreviations mean is google.

Scratch my head

Sydney Morning Herald

sneaky mean and hurtful : cats to mouses

It means Laugh Out Loud :|