From Worms Knowledge Base
This weapon is fired like a gun. It launches one, or a succession of small discs, that do little more than a dent on contact with land but heavy damage on contact with worms. These discs travel in a similar fashion to the arrows from the Longbow, except that they bounce. Furthermore, each bounce raises the amount of damage each disc can do. If a disc fails to hit a worm after a set number of bounces, it explodes, albeit with the power of a handgun bullet, on contact with land.
'Bouncing arrows' shouldn't be a problem in coding. It's a case of calculating the return angle when the discs strike a surface. The computer will need to keep a tab on how many bounces each disc has taken, so that it can calculate how much health damage it can inflinct should it hit a worm.
The ability of each disk to obtain a greater damage potential with each bounce is encouragement for impressive rebound shots, and also discourages the abuse of this weapon, in the same way that many guns are abused, where the user stands next to his victim when firing to obtain maximum damage.
The chaotic nature of discs bouncing around on the landscape, particularly in a cavern or otherwise enclosed area, makes this weapon a good choice for the game as it can easily end in flukey shots, humility and disbelief, like many other weapons of chaotic nature.