My friend's sister was a rather public special snowflake. She is actually a Bridezilla, but this wasn't really related to the wedding (except that BZilla made it related to the wedding.) I copied the following directly from where she made this post, tagging my friend and the other person so it was visible on their walls. I am not friends with the woman - I could literally only see this because she made the post on my friend's wall. I think my friend allowed it to be visible to show the rest of us that she wasn't exaggerating about what an awful person her sister had turned into lately.
"Wow my sister and one of my best friends went to melting pot without me! Nice! Happy wedding week to me!"
Apparently, my friend actually did invite her sister to go along with them, but since it wasn't a pre-planned outing, there wasn't a lot of warning (maybe half a day?) and my friend's sister didn't respond in time to go out to dinner with them.
*Melting Pot is a fancy fondue place that is often considered a special-occasion treat, because it's kind of expensive.