If you want ghosts on your lot this is the easiest way to get them, but you will have to kill some Sims for it... Complete list with Cheats http://sims-online.com/wp-content/uploads/2015/03/death-...
If you have seasons, kill them in Winter by sending them outside in their underwear. It doesn't even need o be a freezing cold day. I did this and was surprised it didn't take very long.