Anything that attracts something. Can be literal or something like chick magnet. Most magnets can attract metal to it.
If strong enough
1.Throw it at someone with a pacemaker.
2.Leave it on train tracks
3.Drop it from a bridge over a freeway and hope it rips through a car roof and penetrates the driver.
Dude, she put 2 really strong magnets between my nuts. I'm sure the results are obvious.