A large shit whose length spans at least the circumference of the inside of the toilet bowl. Extreme relief usually accompanies release of a spanner, as does the occasional bloody anus, sudden weight loss and clogged toilet.
Mass consumption of sunflower seed shells can turn an ordinary spanner into a mace spanner. Resembling the spiky medieval weapon, mace spanners should be avoided at all costs.
"I just ate 4 bowls of granola. There's gonna be a spanner in the toilet tomorrow, I tell you."
Tom:"Dude, I just shat out a wingless 747."
Ron:"No, Tom, you shat a spanner. Good for you. Now unclog the toilet."
Ron:"I told you should have spit out all those sunflower seed shells, Tom."
Tom:"Fuck you, Ron. My intestines are being shredded as we speak. It's only a matter of time before this mace spanner turns my butthole into a bloody, fleshy origami fortune teller"