Important: you will have to have flood and freeze and it will have to be a multiplayer game yourself versing yourself.

First select a map that has a edge thats surrounded by water (for example coloseum of doom). Second get a worm to go to a edge thats surrounded by water.Third when it is that worms turn(or just use worm select) open the weapon panel and select freeze. Fourth when it is the enemys turn make him do flood and the ice cube will still be there but the worm wont be there!