I'm not actually recommending this, it would probably backfire more often than not, but I bet someone has done it

Just think, if you've met a lot of people at various schools, workplaces, clubs, etc..., there are probably people in your past you don't remember. Just go up to someone and start talking to them like you know them, they'll probably pretend to know who you are to avoid embarrassment and then you can reminisce about fake memories of when you were in school together. It wouldn't work on everybody, but there are some people who are very suggestible and easily convinced they remember things that didn't happen