I've been once technically but it was supposed to be twice.
First time was for my ex BFF. It was horrendous. Mostly not due to the bride, although she was a little OTT (to be expected, big stressful day) but one of her sisters who was also a bridesmaid. The sister cried and chucked a tantrum while we were all getting ready. So glad that day was over.
Second time was my brothers wedding to the mother of his child. I was sacked via SMS two days before the wedding by her. She is an evil little "thing". This was the beginning of the end of any relationship I had with my brother. He changed so much and did and said many hurtful things against my parents and I. We haven't spoken to him in years now. There wedding latest the predicted six months.