It is debated that the hatred of Cena began back in 2005 either at ECW One Night Stand 2005 where in the first match the ECW crowd chanted, "Fuck John Cena!", or when Cena faced Chris Jericho that same year on RAW, where the then-WWE crowd was completely 50/50, where a dual chant occurred during the match-up.
Anti-Cena fans are generally adult males and sometimes females from ages 30+; although there are Anti-Cena fans that are as young as 20 and as young as 10 (this is rare though).
It is generally accepted that Anti-Cena fans don't accept the push John Cena receives by WWE promoter Vince McMahon so that the company can maintain a steady profit. The fans seek that other workers in the company receive a similar push, that way all workers can show off of what they have to offer.
Anti-Cena fans will verbally attack a casual fan of the WWE, either before, during, or after a WWE event, or on the internet. These verbal attacks usually criticize a casual fan's knowledge of Professional Wrestling, and how they are single-minded in terms of whom they are cheering for vs. who they should be cheering for. The goal for Anti-Cena fans is to help casual fans gain more knowledge of the sport of Professional Wrestling.
Anti-Cena fan: "You're kidding, right? He barely performs more than 5 moves. Every time he gets in the squared circle."
casual WWE fan: "What's a squared-circle?"
Anti-Cena fan: 0_0