I was playing today (PS4, no cheats) and I had a few WTF moments that arose from the recent Neighborhood Stories update.
My Sim, Jessica (Young Adult), was girlfriends with Angela Pleasant, living in separate houses. Jessica gets a phone call from Angela, where Angela says she found a ring in Jessica's bag and just knows Jessica is going to pop the question, and asks if she should say Yes. I select the affirmative answer, which causes Jessica to be engaged to Angela. I didn't even use the Propose interaction.
Later, Jessica and Angela are chatting. I notice a new friendly interaction called "Discuss expanding the family". Having never seen it before, I want to find out what it is. This causes a notification from Angela, basically saying she has been thinking about it and will talk to Jessica about it. The next game day Jessica gets a phone call from Angela, announcing she is pregnant. Not sure how that happened because neither of them can get the other pregnant, and their last WooHoo was before they got engaged. Three game days later Angela gives birth. Looking at Jessica's genealogy shows that the baby is hers, and the baby's genealogy show both Jessica and Angela as the baby's mother.
The last WTF happened a few game days later. Jessica gets a phone call from one of her other girlfriends, Miko Ojo, and it's the same one about finding a ring. Now Jessica is engaged to two Sims.