WARNING! The practices described on this site are intrinsically hazardous and can cause serious injury or death -- even if done "right". All material is a description of personal practice, and not a recommendation, endorsement, or of such practices in general, nor of specific techniques -- or anything else. Well, we do have some recommendations: Don't engage in these activities. If you do engage, learn and use the best safety practices you can.  Think things through.  Never do these things alone.