A clothes-pin, also known as a clothespin, clothes-peg or just peg, is a device, made of one or two parts, normally used to fasten clothes to a line for drying. In filmmaking jargon, standard wooden clothes-pins are called C-47.
Use as a pervertible
Clothes-pins can be used as pervertibles to pinch the skin like a clamp and thus create a local pain which is usually not too intense but continued - the clothes-pin can simply be attached and left there for as many minutes as wanted. This is mostly done in BDSM. One of the advantages of clothes-pins is that they are available at practically no cost, whereas designated BDSM clamps can be very expensive. Attaching 20, 40 or 60 clamps at once would be unaffordable for most people, but is no problem when clothes-pins are used.
Different types of clothes-pins (e.g. ridged or smooth, wooden, plastic, etc) may be used according to personal preferences. Also the places of use are much left to personal preference, though the skin must be slack enough (or the body part thin enough) to attach a clothes-pin, which is not everywhere the case. Often, many clothes-pins will be put on, one by one, to intensify their cumulated effect. The bottom will often be restrained (e.g. on a St. Andrews cross), and may optionally be blindfolded and/or gagged. Clothes-pins can be combined well with many other BDSM techniques, e.g. whipping, caning, Wartenberg wheels, wax and so on. Like all clamps, they come not so much with corporal punishment connotations but rather with those of (mild) cruelty or torture.
After a clothes-pin has been attached for several minutes the pain tends to become numb. It is revived when the clothes-pin is removed because blood rushes back into the cappillaries.
A string of 20, 50 or even 100 clothes-pins, held together loosely by a cord or light chain, is called a zipper in BDSM. The skin is clipped normally in the clothes-pins. However to remove the clothes-pins, the cord is pulled, causing the pegs to be pulled off the skin one by one. This makes a "zip" sound and comes with a very intense sensation.