"Petticoat" in the context of a porn video refers to a type of undergarment worn by women, typically with layers of fabric or netting, and is sometimes used as a general term for female underwear. It may also refer to a particular style of dress that features this garment, often associated with vintage or historical eras. The tag suggests scenes involving women wearing petticoats or revealing them during intimate activities, which can be a part of fetish play or period-themed content.