To enable this cheat which will help you progress in the game as you don't have to worry about running out of ammo select the grenade symbol at the 'Multiplayer Weapons' menu and then press X on ALL of the weapons that are shown until a symbol appears next to them.
1.] If you play the level on Worms 3D called Grave Danger go round the back of the house,There you should find a piece of land that has steam coming from it just like the graves if you blow it up you should find a easter egg!
2.] If you play the level on Worms 3D called a Quick Fix, go to the keyboard and jump on it then press and hold Square whilst over a letter you will jump vertically up and press it.
Now you must type in the word "team17" together as one word, and hay presto you've got a easter egg!