It stands for 'just kidding'.

And the randomiser strikes again! This time in his own forum...

Randomiser? We randomised 50:50! Before you delete this, shuwan, look further into this post. How about talking about Newgrounds? Nah. Know any games to talk about? Club Penguin! That's it! It's a great game with minigames. Very fun. With shuwan being a mod, I'll try not to waste post pages. The final winner of the 'highest post-count race' is me! But we'll talk about that in any 'Everything else' forum.

(maximum char count is 9,000000000000000000000000000000000000000000)

You're kidding?