Could base it off of certain traits on characters they interact with. Name, gender, event based off of highest stat/skill and time spent with them.
So say you spend a lot of time with Bob, a guy, and one of his highest stats/skills (picked at random) gives you dream event A, where you have a dream about fighting him in an alley or something.
Create a list of dream events for each stat/skill, and a separate version of those lists for each gender. Then toss in a bunch of generic ones and keep adding to the dream list when you feel like it.
