Think of it as your brain being able to communicate without any issues... 100% fluent. As soon as you go to say the word (that you stutter on), a sudden word block rushes over you and it's nearly impossible to say the word. A word block can be somewhat described as if you're trying to remember something, but cannot.. The frustration and anger in trying to find that little byte of information in your mind is what we feel when we're trying to speak.