In Karkat's first conversation with John from Karkat's perspective, John says: "EB: maybe you got what you deserved, you stutid fuckass! " and then says that "stutid" is an in-joke Karkat doesn't get yet. Do we ever see the origin of that?

The only other time stutid is used that I could find was by Terezi talking to Dave.  Dave and Terezi’s inside jokes are notorious for spreading, ever heard of jegus?