I have got a friend who is very impatient and every time you talk to him and you are trying to finish a sentence he keeps saying the first word that comes to his mind, maybe to help you to finish it faster. Sometimes is the word you were about to say but most times is the wrong word.
People usually look at him with anger and probably they think something like: “Thank you, but I do not need you to help me talk, now if you let me continue…” He realises you are not very happy with his interrupting and keeps silent for a few seconds and two or three sentences later he begins to interrupt again.
Needless to say, if you are not perfectly focused on what you are saying, all his interruptions make your mind drift away from the main subject and you end up talking about a totally different thing.
We have told him to stop doing that and probably he would have a better communication with the people around him. He said he is trying, but old habits die hard.
And talking about habits, especially bad ones, I had the awful bad habit of adding salt to my food before even taste it. That is a very common custom that must be avoided at all costs, since the health problems it causes are very dangerous.