I think you're looking for Random Occurrence Scenarios! They used to be very prevalent in TS2 and I use them there all the time still. I adapted the document I use to work with TS4 although I barely use it in this iteration since I play it more like a dollhouse than I do TS2. If you google Random Occurrence Scenarios (or ROS for short) in combination with The Sims 2 (or maybe 3 or 4 might have them as well) you'll find these documents with random events you can roll in your game. It can go from having a picnic to your sim accidentally getting pregnant to having to get married to the sim with the highest relationship. Endless ideas. Very fun!