The act of dropping one's face / forehead into one's hand. Usually accompanied by a "thunk" or a cr a cry of "D'oh!"

Usually written between asteriks in online conversation, to demonstrate an action.

Similar to *headdesk*

The only logical answer to a stupid question or statement.

to hit one's own forehead with your hand/palm, and drag it down one's face. Most often done in frustration or agitation.
Sometimes forcefully done to others for humour purposes.

What I do whenever I read Urban Dictionary.

A spontaneous reaction to an amazingly stupid statement, where the face of the listener meets with his palm in a smacking manner

When someone is so stupid that it makes you speechless, and the only thing you can do is shake your head or facepalm.

usually an image posted on a message board or online blog that expresses disgust over one person's idiocy.