Similar to a facepalm. A facekeyboard occurs when one is on the computer and something either so stupid or frustrating occurs that the user is inclined to bang their head on the keyboard.
Jesus fucking christ my computer is so fucking slow!! *facekeyboard*
When you are chatting on the interwebs to a total dumbfu*k who keeps on arguing with you even though they're obviously wrong.
Related to headdesk and facepalm but only pertains to when using a computer.
...unless you're weird and carry along a keyboard with you, but that's your prerogative.
Ignorant Person: Hey I'm watching this awesome movie. It's called 10 Things I Hate About You.
You: I love that movie. And Heath Ledger.
Stupid Person: What are you talking about?? Heath Ledger is NOT in this movie. You're stupid, I just checked the info guide and he isn't one of the top characters!!