The Paper Cutter when done well feels like its cutting your head off. It is a great technique to have in your arsenal as it can be done in Gi or No Gi. It is effective against wrestlers in particular who tend to be better, in my experience, at making use of near side underhooks to come out of the back door to their knees and attack for front headlocks and guillotines. The Paper Cutter is an excellent defensive submission in this regard. The threat of it can discourage some from even attempting the back door escape. However, the Paper Cutter is easy to get wrong. Matt Thornton Head of SBG recently demonstrated a common mistake, and one that I’ve been making of allowing the angle to close as I show above. You will still get some people to tap but it requires a lot more energy. Instead, you need to keep the angle obtuse and one method I’ve found to ensure this happens is to turn your thumb out to fully flex it externally.