A keybanger is to coast along in an manual carby'd car with the engine off pumping the go pedal 3-4 times then with the car in gear dropping the clutch causing the car to 'roll start' causing a great bang to show you mates you need a new muffler.

Someone who is possessed by clout chasing. The original human is now gone and a demonic entity that feeds on clout is all that is left. An empty shell with no control of their actions, forced to blindly react to situations they think will bring them attention.

A keybanger is a person that has limited success with their sexual escapades in real life, and therefore takes out their sexual frustration online, via trolling, tearing successful people down, or otherwise critical posts. They more vehement their postings, the more virginal they are likely to be.