The Time Warrior - Episode 4
The Probic Vent. Fancy having an Achilles Heal on your neck. A design flaw greater than the exhaust vent on-board the Death Star. Wrap a warm winter scarf too vigorously around your neck and you'll experience temporary paralysis before you can say "Womp Rats". Manly hugs are completely out of the question, just in case a slap on the back creeps above the shoulders. Fine, designer collars are completely ruined by the presence of a flange more befitting the plumbing end of a garden hose.
"I thought peritonitis had something to do with Nicola Bryant."
And what use is it? Is this a vestigial remnant from the time the Clone Masters of Sontar were attempting to integrate the Sontarans with their automatic washing machines. Is it akin to our very own appendix - basically useless, but can still kill you? What happens when a probic vent bursts? Can a Sontaran get peritonitis? I thought that had something to do with Nicola Bryant. I wouldn't particularly relish her bursting on me.
"Which Sontarans were outies and which ones were innies."
It could be the location of scar, left over from the umbilical cord during its time in the gestation tanks. The primary function of the aperture on the collar, at the base of the neck (if you could identify where the neck begins and ends), would be to cover up which Sontarans were outies and which ones were innies. It has been suggested (probably in a Haining book) that the legends of Sontar tell of the time of the Great Uncovering when every single Sontaran soilder shall throw off the shackles of his umbilical shame and parade naked and proud the same as they were when the birthing pipes spat them out, slimy, wet and with their neckbutton on full display.
Just like their hero, Tim Brooke Taylor.
The Bumper Book of Made Up Doctor Who Facts has this to say about part 4 of The Time Warrior: the Sontaran porn industry is enjoying something of a renaissance just about now, with it's new found star Styke Stigson and his ability to manipulate his probic vent in a filthy manner unbecoming a clone of his rank in the Sontaran military junta. It's enough to bring a lump to a Rutan's pipe gland.