The term Jublex is a derogatory term for the the creators of the MMORPG Runescape, Jagex.
The term is believed to have been coined after 2007 when Jagex nerfed (see nerfed) the trade and Player-killing(pking) systems.
Where a bunch of people got really pissed off and started talking smack.
This term is often used on the Official Runescape forums (in the rants section particuarly):
Player 1: Jublex Failz0rz
WBM: This is spam please leave the forums
Player 2: Cool story, bro.
Player 3: Try adjusting the brightness
Player 4: Inb4lock
Player 1: Wowgtfo nubz Jadex nerfed drop rates agen. Jublex needs to un-nerf that shit now.
F-Mod: This thread has been locked as it offers no constructive criticism of game content. Please read the forum code of conduct before you begin posting again.
Guy 1: You call these things chips? Instead of Crispity Crunchy Munchie Crackerjack Snacker Nibbler Snap Crack N' Pop Westpoolchestershireshire Queen's Lovely Jubly Delights? Rather a bit cringe, innit bruv?
Guy 2: wtf