1. Wearing white to a wedding.
This will never ever be okay in my book, unless specifically requested by the bride and groom. Though that is not my cup of tea, if that's what the happy couple wants well then, let's keep them happy. In absolutely any other circumstance, this is tacky as all hell.
2. Not giving a gift.
We all know that weddigs are about celebrating love and two lives joining together and all that jazz. However, it is a gift giving occasion. Showing up to a birthday party without at least a card is terribly distasteful, and showing up for a wedding without one? Way worse. Certainly not naming names, but we had a handful of guests who didn't give any kind of gift or card at our nuptuals. A card with just a nice sentiment and nothing else would have been better!
3. Asking if you can bring someone.
A bride spends long hours deliberating who to invite, who to unfortunately exclude, and who to extend a "guest" invitation to. After making those tough decisions come to brutal ones on how to address the invitations - how to make their intentions clear to avoid awkward conversations like "Can my friend come with me to the wedding?" or "I am newly dating this great guy, I'd really like to bring him.". Let's break it down, if your invitation is addressed to you and someone else by name - you are to bring yourself and that specified someone. You are not to bring anyone of your choice (we had a guest do this at our wedding, a complete strange to both bride and groom and everyone else in attendence). If your invitation is address to you and a guest, you can bring anyone of your choice. If your invitation is addressed to just you, you are to bring yourself and only yourself. Simple enough, yeah?
4. Arriving late.
Wedding invitations normally go out six to eight weeks before the exciting event. Thus, you know exactly what time you are expected to be somewhere for months. Being late is simply rude, and totally unacceptable. Arrive early, allow time for traffic, and ensure respect to the many people involved who planned a wedding that I'm sure they didn't anticipate being interrupted by late attendees. On a related note: attending the ceremony but missing the reception due to other obligations is much more polite than the other way around.
5. Bringing a very small child.
Unless your child is in the wedding, or the bride or groom specifically requested their attendence, very small children do not belong at weddings. Our wedding was only children 13+ due to the nature of 22-year-olds at weddings, and the fact that there would be no tantrums (other than a few bridesmaids who had a few too many cocktails maybe) on my day if I had anything to do with it. Howver, some couples love the idea of dancing with the toddling and young children in their family. However, it is my opinion (and I don't think I'm alone here) that a child under a year simply doesn't belong there (unless of course, they fall into one of the aforementioned categories).
What are your Wedding No Nos?