When you are taking a shit and it is long and narrow like a pencil. This is usually caused by having a tight anus.
I walked in to the stall to find a long narrow shit. Someone must have taken a pencil shit.....
by person uno December 23, 2013
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When you can't clean your anus after pooping no matter how many times you wipe. Usually a mechanical pencil shit is one that takes a long time to come out, so one begins to wipe prematurely before the whole poop has completely dislodged itself from the butt hole.

One's shit keeps refilling like a mechanical pencil: no matter how many times that one wipes, he can't get it clean.
This mechanical pencil shit took two rolls of toilet paper to wipe and I still haven't stopped shitting.

Mentioned by Adam Carolla on the Adam Carolla Podcast 8-11-11
by pzeke August 11, 2011
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The act of drawing on your face/eyebrows to make others believe you have eyebrows/bigger lips

(kylie Jenner Challenge)
Greg:"Have you seen Brittney's face lately bruh?"
Jacob:"Yeah she needs to pencil that shit in, what a slut"
Brittney:"who you guys talking about"

Greg:"some slut"

boys:"laugh in her face"
by falicia420666999 July 17, 2015
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When you pull out during anal and she forgot to shit so you pull out a shit pencil
She gave me a shit pencil last night and I wrote slut on her cheeks
by resperent December 8, 2019
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