When you are playing an FPS game and you shoot someone in the head and get a red hitmarker but that person does not die.
Commonly caused by lag.
P1: lol you missed
P2: OMG DUDE I HIT A HEADSHOT HOW DID YOU NOT DIE... WTF.. I HAD A HEADSHOT HITMARKER
P1: You cant aim bruh
P2: OMFG AGAIN WTF IS WRONG WITH THIS GAME