The Wrong Mermaid

a. A merperson (usually a woman) who is the inverse of prevalent cultural depictions of merpeople: the front half of a fish attached at the waist to the bottom half of a person.
b. A sexual position based on this depiction, in which one partner is immobilized from the waist up, by tight swaddling with blankets.

Behind the door, I was shocked to find The Wrong Mermaid: Gwen immobilized on the couch, torso rolled tightly in Mom's quilt. Compromising as the position was, the back of Denise's head kept me from being forever traumatized by the sight of my pantsless sibling. I shut my eyes and pressed through to the hall.