A sex fart. More often than not unplanned, but a formidable tactic when mastered. When combined with a good wolfbag it can produce the most insane orgasm ever.
If attempting this with a senior citizen, a stain resistant acrylic is recommended on the walls.
"I was fucking Vicary up the poo when the fat slut decided to jump on top. She must weigh close to 300kg cause she pushed the biggest sart out of me."