Something so spectacular in its turditude you can not look away , crap to the nth degree that shines so bright as to entrance

When one is stuck in the restroom due to lack of toilet paper.

an additional activity to accompany the excretion of solid bodily waste.

A crappy activity, or an acitivity that actually involves crap.

The act of passing the time on the crapper by participating in a small, fun activity.

You may read a book, or play angry birds on your smartphone
Shirturbating (exactly how it sounds) may also be a craptivity

Don't forget to wash your hands, after every craptivity!

when you work at kelley buick gmc and cant use a customer bathroom because youre a shop nigger, and the employee bathroom is already in use. So youre stuck waiting around until the only stall available is freed up.

Work done leading to no useful outcome. Work for shit. A play on the words Crap and Activity.
Crapital (money for shit) is usually spent undertaking craptivities.