My name comes from a conversation I had on Steam with a friend. I'm always a kidder and never take anything serious, and one day he just randomly introduced me as "this is my jk-senpai" to a friend because I was always making him laugh. I changed it to be JayKay because saying jk on a forum or in a chat usually means you are kidding and so it would be easier to differentiate name from text talk. I tend to use "-Senpai" on more social media sites and "Gamer" on games or game websites. Not an interesting story at all.