Floating weapon glitch
From Worms Knowledge Base
This is a glitch that works with several weapons, namely those which are supposed to explode on impact with its surroundings - bazooka only being the most prominent one. This glitch makes it possible to place these weapons on a worm where they remain until eventually their timer runs out and they explode. The weapons it works with are Bazooka, Mortar and Petrol Bomb, and theoretically also Homing Missile, Homing Pigeon and Patsy's Magic Bullet, though these will start flying towards the selected destination after about a second.
How to do it
Approach a worm which is standing on horizontal ground and below a ceiling (within reach of a Ninja Rope), and slowly walk up one of its sides. You will notice your worm abruptly moving upward a few pixels - the usual behaviour when it's climbing another worm. Keep moving carefully until exactly two of these upward movements have occurred, then select the Ninja Rope and shoot it straight up at the ceiling. Once it attaches, do not move your worm anymore. Instead, select the weapon you want to place on the opponent's worm and release it.
There is a second way to do this glitch, but it is limited to the Petrol Bomb and requires a little more sleight of hand. Then again, it is not necessary to have the worm standing on horizontal ground. First you'll need to position your worm as close to your opponent's location as possible (e.g. by releasing a Ninja Rope right above it and then tapping the arrow keys to move closer). Now shoot the Ninja Rope straight upward and carefully tap the up arrow, until your worm's position resembles this picture:
Now you can fire the Petrol Bomb, and it should stay motionless on the other worm.
At first, this glitch appears to be useless for tactical purposes. Quite conversely though, it is possible to do around four times as much damage with the mortar as you would shooting it at a worm and hoping for the clusters to hit it. This works only if you do the above climbing up the face of a worm, not its back. This tactic could be very useful in Shopper games, but as it is rather unusual, you'll have to make sure the other players don't dislike the idea of (ab)using glitches.