I have this running machine that has a safety mechanism that is activated by the presence/absence of a magnet.  So when you run you put a magnet on a piece of string on the front, and then clip the other end to your t-shirt, and then if you fall off, the magnet is pulled off and the machine stops.  Pretty standard stuff.  Today however, just as I started, the phone rang, so I pulled the string, and the magnet flew out of the little plastic shell it's in, and I can't find it anywhere.  I then tried all the fridge magnets we have, and none were strong enough, apart from the giant Cartman magnet, but he's too big to fit in the hole without being held in place, which is impossible.  Plus it would be weird to have him staring at me all the time.  I've been racking my brains trying to think of where I can find a small, strong magnet right now!  And I can't!  It's really really really irritating!!