for me its all the times that random old people have died while my sims were going out somewhere, typically its from old age but the last time it happened they drowned in a public pool. the most memorable one was the time my sim was dating xander clavell, and his MOTHER died of old age right outside of the movie theater. if im remembering correctly the date still went well despite the sudden tragedy. these deaths always attract a crowd too, so suddenly theres 20 sims crying their eyes out, a ghost, and the grim reaper all in front of a store or in the park.