Blowouts are when the inside of the ear gets pushed to the outside when you stretch up too fast, skip sizes, or force a plug through. They aren't necessarily bad, they're just annoying and can prevent you from wearing certain plugs. There are things you can to do try and decrease the size of the blowout like massaging the lobe with vitamin e oil or jojoba oil daily. It's what helped mine. If that doesn't work you would either have to just deal with it or have it removed by scalpel. If a blowout happens and you notice it right away you want to size back down, and let it try and heal. Catching it early is the best/easiest way to treat it. It's generally not recommended to keep stretching after you get a blowout because it can get bigger but it kind of varies.
This guy is awesome and does a good job of explaining things too!
http://www.youtube.com/watch?v=QjLkVFbzMyQ