The extremely derisive and annoying sound one says to interrupt boring, unimportant or unnecessary stories or sentences spoken by friends. It is spoken like the work k (Kay), but with an elongated 'a' to complete the word. Often accompanied by a derisive look, a judging mouth click, snapped fingers and the ignoring of the boring person. Supremely effective in rapid fire situations.
(Anytown, World)
Friend1: Dude, so this weekend, me and my mom were watching C-SPAN and this really intere-
Friend2: (snaps fingers, points at Friend1) Kop.
Friend1: Uh, alright, so after that we knitted some socks for my cat Mitt-
Friend2: Kop. (Turns away from boring person)
Friend1: God, I hate you.
KOP is like lol although not standing for anything it means the same but where lol is meaning less u can say kop as an alternative when something is actually funny