A person (s) brain that says or acts without using clear judgement (Unintelligently).
After a stressful day, a person impulsively quits their job, makes a rash comment about a colleague, buys an expensive gadget they can't afford, and decides to try a questionable health cure—ignoring advice and consequences, all without thinking things through, acting like a true BrainCracker.
when you're holding up your phone and making faces at it, as though you are taking a selfie, but you're really taking a picture of the person across from you or the wall or anything else that seems interesting but you don't want to be caught dead taking a picture of.
This action is often made more convincing by wiggling the eyebrows or opening the mouth, to pretend you're trying to get a Snapchat filter to work.