The Jack-O-cavern was a secret area on Tinkatolli for the 2011 Halloween Party only. It was first seen on October 30th 2011, and could only be accessed if you completed the Stinkarinth from Stinkatolli.
On your first entry you win a very rare badge for getting into the secret room. Due to the fact it says only beta players and TinkaTesters will have this badge, it probably won't be returning next year.
Inside the Jack-O-CavernEdit
The Jack-O-Cavern is basically a giant pumpkin and the inside is like the inside of a pumpkin, and there's a candle. Inside there you find lots of energy sources like Popcorn and various flavours of jelly beans.