We are living in a world, where freedom of speech is stretched to the limit. We can say just about anything and get away with it. {Or can we?}
Jesus said in verses 36 and 37 that every idle word that men spoke, they would have to give an account of in the day of judgment. For by their words they will either be justified or condemned.
It seems to me that Jesus is warning us to watch what we say. The child of God should be very careful how they speak. There are people listening and watching us all the time. Many times what they hear and see is anything but CHRISTLIKE. When we are with other people, we should always ask the Lord to set a watch on our mouths. If we are in a situation where we can't think of anything good to say, then we should say nothing at all and quietly walk away.