When you are having a life threatening shit. It partially comes out of your anus and gets stuck because it is too big and strong to slide out easily.

The anus cannot cut through it. It will not go back inside. The only way is to power through and hope you do not blow your anus out. If you are lucky this ordeal will be over within minutes.
It won't come out, it won't go back, it's Turtle's heads! - Turtles' Heads by the Macc Lads.
by For Christ Sake! December 4, 2016
The first part of a turd that will poke itself out for air, when yo' ass is fit to bust.
'When the turtle's head pops out, you're on borrowed time...'
by ant July 27, 2004
Turtle heading is when you need to take a shit and it is starting to peer out of your ass. Like a turtle coming out of his shell.
"Hey bro let's move!"
"Hold on a sec I need to take a dump."
"Can't you just hold it?"
"Naw man I'm turtle heading!"
by Hemlok February 16, 2009
Bro we really need to find a shitter! I've been Turtle Heading for the last 20 minutes! If I don't get there soon Mr. Hankey is gonna come visit.
by RoyalTokes July 8, 2018
(verb – present participle) The act of experiencing the summit of a crusty turd protruding from your sphincter (a turtle head); to really need a crap
Onlooker: "Why are you walking so strangely?"
Protagonist: "I'm turtle-heading, if I don't find a toilet soon I'm going to purge all over my pants."
by Don de Mookster October 27, 2008
A distinct piece of feces pertruding out of a homosapiens rectum. The "piece" is slightly cone shaped and peeking out as would a common turtle from its shell.
Dude I gotta crap real bad, I got a turtle head!
by terd-dul hed October 27, 2003