Complex sentence: A muzzle gag is a form of gag used in BDSM activities, that resembles a muzzle used on animals, with a flexible pad which straps over the mouth, and sometimes also around the cheeks and chin.
Split into simpler sentences: A muzzle gag is a form of gag used in BDSM activities. It is so called because it resembles a muzzle used on animals, with a flexible pad which straps over the mouth, and sometimes also around the cheeks and chin.