Head bondage
From wipipedia.org

Head bondage, in BDSM play, may refer to one of two techniques.
- It may refer to encasing the head in a bondage hood, or a head harness with blindfold and gag, possibly with a wide, stiff collar round the neck (posture collar) to restrict movement of the head.
- It may refer to pulling the head backwards by hair bondage or a rope attached to the back or top of a hood or head harness. This is sometimes done as part of a hogtie, especially a pretzel hogtie. It is also possible to use a rope attached to a blindfold or gag, but this is usually less secure and may cause excessive pressure on a small part of the face; in particular, with a gag, the corners of the mouth may be injured. With this technique, severe or prolonged bondage usually causes a stiff neck and care is needed to avoid any permanent injury.