Yeah, special forces shit. Remember, K-Bar knives are a little longer than what we are talking about, but it is possible. The target is the pulmonary artery, or better, the aorta. They are bisected when you make the flip. It’s not as easy as it sounds. These guys practice under experts for the whole time they are in. You better know where the sternum ends here, know your anatomy, and have good aim under stress, or you will hit cartilage as hard as bone and only piss off your opponent even more.
You’ve also just given him a pretty strong signal that he is now in a fight for his life. And now you are within his grasp. And even if you do hit your mark, what do you do in the twenty or so seconds it takes him to lose consciousness? That is a long time and adrenaline is a wonderful thing. I wouldn’t attempt this unless it was my absolute last possible chance. People watch way too many action films.
There is a second and third maneuver to this that your boy forgot to tell you about. In one swift move, whether you hit your mark or not, you stomp and crush his arch, then come up with same leg and knee him in the crotch. Then you run for your life.