Breast torture
From wipipedia.org

Breast torture, also known as tit torture (or simply TT), is the practice of inflicting pain on the breasts or nipples of a sub. Nipple torture is a form of breast torture. It is practised by gay and straight people of boths sexes and the gentler techniques are very popular in SM play.
Breast torture covers a wide variety of techniques of varying levels of risk to the victim which can include:
- Nipple torture (See the article on nipple torture for a discussion of the techniques than can be used).
- Use of suction cups.
- Binding of the breasts with rope or straps (see breast bondage).
- Beating or caning the breast.
- Inserting needles into the breasts.
- Using a violet wand to apply static electricity.
- Using a TENS unit to apply high frequency electriciry.
- Suspension of the sub by the breasts.
- Clothes pegs or zippers applied to the breast.
- Dripping hot wax on the breasts.
- Applying ice or freezing sprays to the breast.
- Biting and pinching the breasts
As with any form of SM play, the participants need to be aware of the risks involved and be prepared to proceed cautiously with their experimentation.