Do not say the regretful words
Speaking can state a person's appearance, we should keep attention on it before you speak. Ancient teaching said "disease goes through the mouth, disaster comes from the mouth", which it’s the truth.
As a modern man kept talking every day, we must be very careful to avoid trouble.
From the using words and content, we can understand this person's character. Ancients advocate to speak less, so there is a proverb "silence is golden".
But the talking between good friends all night can not be said bad, in this situation, you can chat everything what you want, and do not worry about this causes unhappiness for others.
Similar proverbs, just like"Silence is golden" is not to warn everyone not to speak, but hope you know that keep more attention before you comment.
As for "disaster comes from the mouth", means once the relationship between friends becomes close, in this you can talk everything what you want, However, everyone's emotions are changing at any time, when the mood is not good, the body is not comfortable, there is trouble, when have concerns, then the behavior is usually different with normal. Therefore, even if for close friends, we should pay attention to the proper use of vocabulary and etiquette.
For older people, or people of high status peers, with the same year, not interested party, originally works, even if they become more and more close in the future, that will be not changed.And the rude, vulgar words must not be used. If you let the other side feel that they are not sincere when speak, communication will be very difficult to continue. People are emotional animals, it is easy to shake once the environment or positions changed, so, the best what is do not say the regretful words.