The Weasel Shot is a specific shot used in foosball. It is performed by trapping the ball against a wall with one of your men. With the ball trapped against the wall you slam your man against the wall and the ball. If done correctly it will shoot forward very fast at a hard to block angle.
The Weasel Shot is best used by your 5 Man Rod, as it tends to shoot directly towards your opponents goal.
Added note about the The Weasel Shot: Be certain the ball is slightly towards the direction you want it shot at. You don't want it flying back towards your goal do you?