I don't think I have ever had an MRI before, but I am sure one day I will for one thing or another.   If you ever wondered just how powerful the magnet is inside, well this video will show you that it's beyond imagination.  Metal objects in the same room with an MRI machine become dangerous projectiles, and the pulling force is amazing.  Of course this is all very safe, when you have tests done, and follow the rules, but it's nice to be aware of the situation.