What is the nastiest/meanest thing you've ever said to someone else?

I cut down this couple at my parents church years ago. This was when I was first starting to transition so we are going several years back. I got dragged along by my parents to some fundraising event at the church they go to. Got told by the woman in the couple that changing my body into something it is not is a sin blah blah blah. Basically they were saying I was a shameful creature. Well this couple is known for having fertility issues and she was undergoing various surgeries to have a baby. I threw her own words back at her and made her cry. I told her that she's changing her body around to have a baby and that's sinful because your body is not naturally able to have children. If it's not natural it must be a sin right? I also said it's a waste of money and resources to force your body to have something you obviously can't have. I added in it must not be god's will for you to be a mother huh.

Made her cry and her husband looked like he wanted to smack the crap out of me by the way he just glared at me after. You want to be rude and come for me I will go for the attack. I am not known for my kindness you know. Needless to say I was never invited back by the church or my parents. They didn't speak to me for awhile because I had brought them shame in front of their friends. Oh well

Yes, I can be downright nasty does this surprise you?