I like arguing with people. Sometimes I'll act dumb and use the Socratic method of asking seemingly innocuous questions that tease apart the person's position. Sometimes I'll be aggressive in pointing out the inconsistency of their position and condescendingly laugh at them as I do it. Either way can be entertaining and fun; and more to the point of this post - it is usually extremely easy.
99.9% of the opinions of 99.9% of the people are arrived at through instinct not logic. The person then mentally commits to that opinion and looks for arguments to justify their position. I have encountered very few well thought out, consistent, opinions.
I cannot emphasise enough the truth of this observation; it seems to simply be how the human mind works. It takes self knowledge and a willingness to re-evaluate every opinion you hold dear to not fall into the same trap.
So if you want to stop talking out your ass, bring a little logic to your thoughts. Think about it and then arrive at a conclusion, don't have an opinion and then think about it.