Lack of situational awareness can get get you killed.
Here we have a surveillance video of a verbal dispute that turned deadly for one of the participants in Ecuador. The victim made several mistakes. Thinking it's just a 'pissing' match (which he should have just attempted to walk away from in the first place) he allows the younger man to get right up in front of him. He then compounds this by staring the younger man in the face instead of watching the man's hands. You can watch as the younger man keeps his right hand blocked to his victims view by keeping the right side of his body angled away from the victim. You can then watch him very casually slip the knife from either his right pocket or the waistband of his pants.
Something as simple as a step to the side away from the younger man or even having his arms up in the old 'Jack Benny' stance with one arm across the body and the other with it's hand by his face or neck would have been allowed him to block or deflect the stab. What he could or would have done after that is another issue, but at least he would have been alive to either fight back or run away.
Just so you know, this video is pretty graphic towards the end