facepalm

noun

Pronunciation: /ˈfeɪsˌpɑː(l)m/

Etymology: From face + palm. Attested since at least 2001.

A gesture of bringing one or both palms to the face, with various interpretations including exasperation, chagrin, frustration, embarrassment (one's own or vicarious), etc.
“[Cue: William Tell Overture] [sound of Frank Zappa's “San Ber'dino” being played on Japanese instruments] [Kevin (the Muse): “Wargh! It SAID _William Tell!”] [Cantata11 (walking up with a koto): “Oof. Sorry. It's just that the girls had gotten warmed up to the other thingy...”] [Kevin: “William _Tell_, 11.” (facepalm)]”
““Do you think Carl Sagan might be available?” There was a mass-facepalm. “No.” they chorused.”

Etymology: From face + palm. Attested since at least 2001.

To bring the palm of one’s hand to one’s face as an expression of mixed humor and disbelief, disgust or shame; for example, when one is caught off-guard with a particularly bad pun.
“Christie blinked, then *looked* at Steven. “Do you have any idea what might be different?” “Um... No? Christie facepalmed. “Well, her hair was red this morning, right? It's blonde now. You figure it out.””
““Yay! I know you! You're Nicholas Lee, the detective who got fired 'cos of us!” Nina exclaimed happily. Lee facepalmed. “Arrgh...” “Nina...” Tris muttered. “Let's quit while we're ahead, okay?””
To bring one’s face down to one’s cupped hand or hands.