It’s an affectionate nickname for Hexbear. You might know that they behave like a bunch of 4channers, throwing and smearing their poop around; and Hex=>6… both combined make 6chan.
When your insults are so fucking weak that you have to explain what you're on about to literally every person you say them to it's time to get a new shtick.
I never liked Seinfeld, not even in the 90s, but when he started raging about "triggered" college students not finding his stale set from the 90s funny decades later, I felt vindicated. And of course I soon found out that he was a kiddie creeper all along.