I've killed a lot of sims for the Black Widow Challenge and I've gotta say my favorite way to kill sims is either drowning or hysteria. I've tried starving but it takes soooo long omg. But what meth...
Vampire sims have a great ability to alter someone's mood to the extreme, and it kills so many sims. It's the only way I've found for one sim to kill another without mods, and I love it.