@375 Step one: Learn hypnosis. I'm joking a bit, but it isn't all that difficult. There's an entire subreddit dedicated to erotic hypnosis. It helps if, like me, you have a voice that puts people to sleep. It also helps if you're a writer, because hypnosis is much more effective if you use imagery. You'll need someone who can be hypnotized (not uncommon) and they need to be able to trust you.
Beyond that, there are few limits. Want to make the subject more ticklish? You can do that. Want to make them forget they can speak English, or make them roleplay Margaret Thatcher? Totally doable. The more imaginative the subject, the better.
It's not mind-control because the subject always gives consent and can take it back at any time. But it's still amazing. I've even used hypnosis to make allergies go away, although admittedly these were never life-threatening allergies.
@wumblebumarts You know it my dude.
@hotsubsandwich Putting the "sub" in hotsubsandwich?