Bum spider 

Where a clump of poo gets stuck to your anal hair. You grab hold of said poo and pull it until it is removed. The poo takes with it a number of anal hairs during the removal which when placed in the palm of your hand looks like a spider. This is now a bum spider and can be used to chase your mates around and you will get similar reactions as if it was a normal spider.

Look at the size of this bum spider I just took out of my ass crack.

Bum spider by Northern1000 January 9, 2018

chewy black bum spider 

a nugget of poo with pubes stuck in it that is discovered whilst going down on someone.

dave: dude i went down on this girl i met at the bar last night
gerald: good times?
dave: no way when i came up i realised i had something in my teeth..
gerald: what was it?
dave: a chewy black bum spider.

chewy black bum spider by munkybutt March 15, 2008

Bum Spiders 

1. When sitting in a park and your friend discovers a spider approaching your lower back going for your bum. This spider could be aiming to actually get inside your bum, therefore becoming a bum spider.

2. An imaginary STI where if you have anal sex too much, spiders will become attracted to your bum, then being able to be passed on to someone else who has anal sex with you.

Helena: "DAMN there's a spider going towards your ass!"

Doug: "SHIT damn bum spiders!!"

Bum Spiders by HelenaLexxiFoxxx September 29, 2010

Bum Spiders 

Spiders from the Bum

Person 1: You have Bum Spiders
Person 2: oh no

Bum Spiders by Bum Spider Lover February 6, 2020