A sex act wherein the male sits on top of the females stomach. He then precedes to "titty fuck" her, and while doing so, farts on her stomach.
(The act may also be performed female on female,with use of a strap on, or male on male, provided the partners bosoms are large enough to host the act of "titty fucking")
If this includes going past farting, and into releasing excrement, it is referred to as a "Filthy Collins ala king"
Dude, you'll never believe it. I got Laura to let me give her the filthy collins. It sounded like I was opening the world's largest sleeping bag"
"I feel so bad. I was giving her the filthy collins and I totally ala kinged her"