When an individual is urinating into another individuals mouth and while doing so the individual urinating hits the individual swallowing in the back of the head causing them to cough the urine out of their nose, thus a yellow dragon.
I use to dislike swallowing that Gelmini's urine though he loved it when I did, but once he gave me a yellow dragon I refused to ever let him pee on or near me again.
You take a mixture of urine, snot, and enamel fluid from tubgirl's asshole and you use it as lubricant for fucking pleasures. The yellow dragon is not as dangerous at the others, but goddamn does it smell.
As I inserted my yellow dragonified penis into her anus, chunks of who knows what flew everywhere, bathing us both in a brown and yellow shower of glory.