An Internet acronym used in text (SMS) messaging and in social media posts such as appear on Twitter and Facebook. Although many people believe it stands for "shake my head" or "shaking my head" (as in disbelief or disdain), the true meaning is "so much hate."
However, due to the widespread use of "smh" from those who have learned its meaning incorrectly, it can be assumed that many who use it do so in the erroneous meaning of "shaking my head." It can usually be read either way.
"smh" is similar in meaning to "fml", but more angry than despairing.
"My little brother keeps telling everyone he'll be able to play in the Super Bowl next year, and he's only fourteen! smh"
"The government has instituted a new tax on, get this, twisty-ties. smh"