Hidden Weapons
At the title screen, type "TOTAL WORMAGE" to gain all the hidden weapons. If you did it right, you will hear a sheep saying baaa and the title screen turns green.
When Push Comes to Shove
When it is your turn and you see someone near an edge, come up right behind them and press the left, then right arrows quick. If you did the code correctly, your worm should push the other one off the side!