That little part of your
brain that
will hear or think of something hilarious but inappropriate, which
will act as its ignition. It is then powered by your attempts to ignore it, and
will accelerate, never reaching a terminal speed and only stopping when you blurt out whatever thought started it at the worst possible moment. It is related - but not linked to - that part of your
brain that inexorably broadcasts horrific images to the rest of your brain at inconvenient times, for example: images of corpses while eating, images of your mum during sex etc.
Called 'man motor' because there is no evidence of this phenomenon ever occurring in females.
Your idiot thoughts during a funeral: Hey, that dude who was killed in a horrific car accident at the age of
25's wife's face kinda looks like a pan-fried
vagina.
Man motor: *click! whirr...* Yep, pan-fried
vagina. Probably should tell someone that.
That one part of your brain responsible for - and completely incapable of - inhibition: No, that's horrible.
Man Motor: *Whirrrrrrrrrrrr...* Nah, go on, it'll be funny. You love causing egregious grief.
Inhibition: No, Man Motor, no.
Man Motor *WHHIIRRRRRRRR...* Come on, you don't know how people
will react, they might like it.
Inhibition: Please stop trying to-
Man Motor: *WWWHHHHHIIIIIRRRRRRRRRRR...* PAN-FRIED
VAGINA PAN-FRIED
VAGINA PAN-FRIED VAGINA
You: HEY, DEAD MAN'S WIFE, YOU LOOK LIKE A PAN-FRIED VAGINA!
Everyone: *mortified gasps*
You, at the behest of your Man Motor: So... Anyone wanna fuck?