Pig reflex 

Not exactly a reflex, but it's a term used to describe the phenomenon of feeling sleepy after eating a heavy meal.

Once I cleared the buffet table, my pig reflexes were acting up.

Pig reflex by newton12 April 19, 2013

Pig Reflex 

"pig" referring to the 50's slang term for police;

the automatic instant reaction when you see a cop to put your foot on the break and act unsuspicious

Friend 1- "dude why did you just slam on the breaks when we passed the cop?"

friend 2-"sorry my pig reflex was acting up."

Pig Reflex by Shitsandgiggles1107 June 5, 2011