Typically used as an action word to describe the reaction to unexplainable, unreasonable, unnecessary, dumb things that ones do. It has the simlar meaning to "face palm" but in the more extreme way. As Púm in ancient Greeks typically means "unnecessary stupidity" or "unnecessary dumb behaviour" the word is then used together with the word "face" to create the word "facepum" because it has similar pronunciation as face palm. The word it's now commonly used as an insulting and criticising way to react to ones behaviour or action.
by Polam May 22, 2016