Snatch is one of the more common methods of drawing and presenting one's sidearm
from concealment. It is most often used when one is going to draw from the strongside
and is wearing a closed shirt or vest to cover the sidearm
It involves letting your weak hand (the one opposite your strongside hand) to grab the part of your shirt or vest that is covering the sidearm upwards and then proceeding to draw with your strong hand. While this is a bit slower than drawing with an open suit or vest, it does allow one to dress lighter and to appear casual yet still be able to carry a concealed weapon.
The name most probably came from the guy Ken Hackathorn who is one of the founders of IDPA and is also a combat shooting instructor. Thanks to borgo for this.