What are some examples of bad manners?

Bad manners at a wedding often come from thoughtlessness. Not RSVPing by the date is a common one, because it forces the couple to chase you and leaves them guessing for the caterer. Wearing white or anything that could outshine the couple is another, as it can look like you are competing for attention. Bringing an uninvited guest, whether a partner, child, or friend, puts pressure on seating and catering. Being visibly drunk, interrupting speeches, or starting arguments ruins the atmosphere for everyone. Using your phone during the ceremony, especially with the flash on, is rude and can ruin professional photos. Also, posting photos or videos on social media before the couple has posted their own is seen as stealing their thunder. Other examples include complaining about the food, the venue, or the music within earshot of the couple, and leaving early without saying goodbye. If you have a problem, handle it quietly. The day is not about you, and your job is to support the couple, not to add stress.