The Tueller Drill is when 2 men line face each other from about 21 feet away. One man is armed with a knife and the other a gun (in holster or whatever carry method he usually utilizes). At the signal the man with the knife rushes the man armed with the gun and attempts to stab him with getting shot. The man with the gun attempts to draw and fire without getting stabbed. This rarely goes well for the man with the gun unless he utilizes explosive movement. I've been trying to find the video of it and until now have been unsuccessful. Finally found a version of it in this Pekiti Tirsia video although they don't appear to be spaced out the full 21 feet.