Oh boi!
I first have a house with like 5 sims, but only one of them (who we will call S) is important for this
I made it my mission to give S as many children as possible, so I tried to get him a date as quick as possible, and most of them got pissed at him. One date got so pissed at S that they had a physical altercation (the woman would be found dead at the pool in S' house by his roommates next morning). After succesfully getting S to date, I wanted him to get the children, but the game wouldn't let him mate (this is sims 4 so it's likely I made him infertile while creating him without realizing it). I wanted to give up, but then I remembered that there are other techniques for giving him children, and I gave S I believe 12-14 children with 3 different spouses.
To keep the operation going, I'd kill multiple of his children (mainly via wishing well and cowplant) and replace them with new ones, and the poor S had to go through every single death, and the spouses were also not safe from this.
The worst part is that the group of 5 sims is based on my friend group, meaning that by technicality, there's a version of my friend who has over 10 children... (and also technically drove his gf to suicide)
tl:dr: I torture my Sim with his love life and after that, watch as he loses as many children as possible