An acronym which is a variant of SMH; it means "shaking my dick head."
Instead up moving your head you put your hand infront of you and shake it while saying "Shaking my Head."
Me: Wanna come over?
Her : I can'ttoday.
Me : SMDH.
This is an Acronym that originally meant "Silently Masturbating During Homework". It was converted into "Shaking My Damn Head" when a Facebook member who often used this term was asked, "What does that mean?". The individual responded with a quick and witty answer. "Shaking My Damn Head". The individual who asked what SMDH means responded, "You sure do shake your damn head a lot".
Insert derogatory term here.Insert teacher name here gave me 35 pages to read from Insert book title. SMDH...