How do you get level 256 in castle crashers

You have to have another 256, another controller, Xbox Live, and another gold account.

• Have the 256 make a private lobby.
• Sign the second controller into the other account.
• Join the 256 game.
• When the timer to start the game is at 2 have YOUR account leave the game (press B)
• Play a level with the other account to save progress (a short one)

And that's all.