Its a dutch word and his full nickname used to be de_zeurkous.
He used to be active in the Doom community too.
https://www.doomworld.com/files/file/11315-the-best-of-de-zeurkous-compilation/
https://www.doomworld.com/profile/380-de_zeurkous/
https://www.doomworld.com/news/help-wanted-r1272/...