The most common way I know to set up for SBK is this one:
However, it takes some time to set up, and some people have trouble getting the strap at the right place on their sacrum. They may feel pinching in the lower back or just suffer through the pose. So here is an alternative:
Here's another one:
The pose can also be changed to suit the stretch.
What about making the pose more uncomfortable for everyone? Here you go:
And now my new favorite way to do SBK - prone. I learned this from Arun this past summer. I can't get enough of it.
Place a belt just like regular SBK, but bring the belt as low down as possible on the buttocks. Please ignore the strap you see going over my leg; it is the tail and has nothing to do with placement of the strap. Pretty amazing. If you are a little tight, like my husband, your pose may look more like this:
How do you come out of this? As best you can.
If you leave your set-up unattended, someone might come and take it.