So, at first, you have to finish the game to buy it. It costs 5,000 coins.
Before you get the ToW, you get a menu button that says "Enter Cheat Code". If the code is invalid, it'll say "Invalid Code". You write down the code in the bar that has squiggly lines surrounding it. Before you get the ToW, the only codes you have are "future" and "trickedout".
No matter what type of case you use, the code works. First, when you get the ToW to 50 height, the ToW says "To celebrate i'm 50 feet tall, put daisies in the menu for Enter Cheat code for zombies to drop daisies when they die!"