Why so cranky about a nickname?
6K may be challenging to those who struggle with counting or recognizing letters of the alphabet. But it's bespoke to him and unique in a way that reflects his unusual name. IMHO it's also far more clever and interesting than just his initials, or the uninspired "Upie" that I hear his teammates sometimes use.
Whichever one you prefer though, using words like "garbage" and "dumb"? About something as trivial as professional athlete's nickname? Makes it sound like you should consider switching to decaf.
