"FacePalm" means "(sometimes also face-palm or face palm) is the physical gesture of placing one's hand flat across one's face or lowering one's face into one's hand or hands. The gesture is found in many cultures as a display of frustration, embarrassment,[1] shock, or surprise.[2]" Source
"FacePlant" is a similar idea. It is used to described a failed attempt at something, I tend to use it as a strong description for a failed argument than a facepalm. It's not just a failure it's an epic failure.
