You should thank friends for inviting you to do things
Brian is at a friend's party.
Brian wants to go home and get ready for work tomorrow.
Brian makes sure to tell his friends goodbye and shows his appreciation for being invited to the party.
Brian slips out the back door without saying goodbye to anyone.
Brian's friends are glad he had a good time and are sure to invite him to their next party.
Brian's friends think he is rude and don't invite him next time.