Long time lurker, and I finally get to share my story... (Sorry for the scribbles, I covered her tattoos to increase anonymity)
My BIL's girlfriend was soooo messy at my very small, intimate wedding. She cried throughout the rehearsal, but wouldn't talk about why. At the rehearsal dinner she hid in the bathroom saying she "didn't want the attention on her", and got upset when I tried to talk to her about what was going on to be supportive. I figured she would get through that night, and we would be ok the next day, but I was TOTALLY wrong.
At our wedding, she got unbelievably drunk immediately, was crying on and off the whole day, taking selfies of herself on the toilet at the reception and posting them on Snapchat with captions like "when you're already drunk at the function", etc. I was trying to ignore it, but my BIL was the best man, and it was hard for me and my friends not to notice how distracted and concerned he was instead of enjoying his brother's wedding. He spent the majority of the time at the reception standing outside the women's bathroom.
And on top of everything... She wore this. I had a really hard time because I believe women should be able to wear what they want and not be shamed for it, while being appropriate for the setting. Now, we didn't have a dress code, it was more come-as-you-are expectation, so you can absolutely say this was kind of on us. We wanted people to be comfortable, and I wasn't worried that they were going to not be fully covered...
Since then, she cheated on my BIL, kicked him out of their apartment so he had to withdraw from classes to move cities back home, then strung him along for months saying she wanted to get back together with him while sleeping with the guy she cheated with, AND lied to their friends about the entire situation to turn them against him. They all finally figured it out, and have removed her from the social circle completely. So, I now feel comfortable shaming her anonymously :)
PS - yes, she caught my bouquet.