1. The mucilaginous issue of reverse peristalsis, in cases where said vermiculation is the denouement of overly ambitious fellatio.
2. The sudden, steaming end of a throat-fuck.
3. When you get a blowjob from a drunk girl and she throws up in the middle of it.
"I kept a firm grip on his ears and pulled until I felt the warm lap blanket flowing over my legs."