This is a sexual act usually done by oneself. Ideally, it is done in a desert environment after eating spicy food yet can be done anywhere. After having a bowel movement, wipe some of the fecal matter over your testicles, then
lie outside on your back with legs spread. The fecal matter
will attract flies which shall land and '
dance' on your testicles thus causes a tingly or arousing sensation.
After I had some really spicy Mexican food, I wiped the other way once and speared my boys, then lied outside with my legs spread a little. The flies came right away and jumped
all over it. They gave me the best Mexican
Sack Dance ever.