If you have lost the rear but still have the front, dont chop the throttle or you could high side. Stay on the bike and steer it, dont add throttle just stay with it and you can save it. I highly suggest every street rider should put on some gear and ride a dirt bike to learn some techniques that will save your *** on the street. Create situations on dirt, rear spinning out, rear locked up ect. Practice practice. The first time the rear goes on you riding on the street, most people panic and let it go or chop the throttle and that can be even worse. The dirt is much kinder for learning these techniques that need to be reflex.