Crotch rope

"Panty tie"
by Robin Roberts

A crotch rope (also known an a Crupper {in Europe} and Sakuranbo (in Japanese bondage) and 'Panty tie' (on the US West Coast) is a form of a bondage rope harness, where a basic tie encircles the waist, and a second, perpendicular rope goes through the legs from front to back.

In Japanese bondage a crotch rope is tied in such a way as to rub against the genitals. The aim is to generate thoughts of sexual submission and excitement in the person thus tied.

The same purpose may exist for Western-style bondage, which also uses them for anchorage when restraining a victim or support during suspension bondage or on a St. Andrew's cross.

Depending upon how tight the ropes are tied, the size of the rope, and the length of time they are worn:

it could be used to hold a vibrator or butt-plug in place,
it could be erotic (if the rope is medium size and made of cotton or nylon)
it could be a punishment (if the rope were very thin or made of a rough cordage)

"We" were doing demonstrations of a Panty Tie at the 2006 Folsom Street Fair. Someone in the audience asked about is purpose. I showed how a vibrator could be woven into the harness. Someone else asked about its effectiveness. Being a "good instructor", I turned the vibrator on medium. I explained to the audience the vibrator was actually causing the entire harness to vibrate. About five minutes later, she began to orgasm, Her legs became rubbery and I had to literally hold her upright.