I hate when people are nervy like that. My MIL took it upon herself to invite a girl I HATED from high school to a shower she hosted without consulting me. This girl was definitely not on my guest list for the wedding because she's always had a thing for my husband and I can't stand her. She gave me a very inappropriate gift in a room full of my friends' parents and talked about her upcoming wedding for the entire shower. When I told my MIL afterwards that she would not be at the wedding, I caught hell. I was called a money-grubber, a bitch, any name you can think of. I sent the girl's gift back with a note explaining that I couldn't accept it since she wouldn't be a guest at the wedding and I apologized for her mistaken invitation to the shower. Needless to say, I wasn't well-liked by some people for a few weeks afterwards. I honestly didn't care, though, because I would not have been happy with her at my wedding.
I had sweet revenge when I heard that her wedding was very trashy, though. She had karaoke at her reception, but it wasn't even a professional karaoke guy. It was just a boom box with her uncle putting CDs on with a microphone. I laughed for days after that