From Worms Knowledge Base
A zero-range weapon, requiring your worm to be almost touching the victim. When activated this weapon allows you to not only see what weapons the enemy has, but allows you to select a weapon, remove it from their inventory and add it to your own. The turn ends after this has been done.
The animation for this would be tricky but the effect would or should not be hard to implement. In order to view and select an enemy weapon, the enemy's weapon inventory could be displayed a second side-bar scrolling in from the left. After a weapon has been selected it retracts. This weapon seems almost cheap in that it requires no real skill to use, except for judging when to use it (if you know the enemy is in possession of a super weapon) but comes with a great risk. After using the weapon you have left your worm just a stone's throw away from the enemy you just attacked, and with no attack of your own to have changed his situation, he's in the perfect position to attack you before you get chance to use his weapon against him. Or, he could steal your weapon back if he has a Pick Pocket. That is, if it's his turn.
This weapon is very cheap and easy, but comes at the price of a fairly unproductive turn. And the animation would require some thought.
If you don't choose what you pickpocket, it would be better and easier to animate: worm puts hand on enemy worm and makes 'aha lets see what we got' face.