How do I remove a security tag from clothes?

I just bought an RVCA jacket at Sun Diego and arrived home to find the security sensor tag still snugly attached to the jacket that the lady forgot to take off. It’s right on the seam of where the jacket meets the hood, I tried prying it off but there’s no way it’s nudging, and I don’t want to tear the jacket. I don’t have the receipt on me and already ripped off the paper tag so I don’t necessarily have the option of going back in the store and having them remove it for me. Lame.
I heard of a couple options from some friends, that I can buy a magnet or apparently there’s a certain kind of hook that will remove the sensor. However, I have no idea what kind of magnet I need to get, how big it should be, or WHERE I can get it. Can you guys help? Or where can I get this ‘infamous hook’??