A baisermouillé (onomatopoeic initialism) for "Fart Trapped In Thong." It is both a word made from the initials, and (supposedly) the sound made by said flatulence.
As she stepped in front of the interview panel, her nervous stomach and lucky undies conspired to make the tiniest "ftit."
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.