What does the text abreviation smh or smf mean?

In a text message the abbreviation SMH stands for Shaking My Head; it's used as a sign of disbelief. The abbreviation SMF can have one of several meanings, depending on the context in which it was used. It can mean So Much Fun (having a great day), Snapping my fingers (to a song), Shaking my Fist (in anger), or slapping my forehead (in disbelief, or from an epiphany).

Wednesday, February 01 2012
Source: http://www.all-acronyms.com/SMH