A utility gag is a mouth gag with an attachment point at the mouthpiece that fits useful accessories. Utility gags typically fit items such as ash trays, toilet brushes, serving trays, feather dusters, etc.
More About Utility Gag
Utility gags are used in Dominant/submissive BDSM play in which the submissive is dehumanized and used for utilitarian purposes. This is sometimes referred to as utility D/s play. Other types of utility play may consist of the submissive acting as a footstool, table, or household tool.