bowl stainer 

brown streaks left in the bowl after taking a crap

I peered into the stall and saw one of my coworkers bowl staining.

bowl stainer by brian meade February 20, 2004

Sloppy bowl stainer 

When you do a poo and it is so liquid like, it comes out as slop and stains the toilet bowl even after a couple of flushes.

Dont use the toilet wait for the cleaners to clean it. I just did a sloppy bowl stainer.

Sloppy bowl stainer by Lbigfella August 24, 2016

bowlstainer

A crap so bad it is said to stain the toilet bowl. This can be due to the size of the crap, or, alternatively, because of the painful feeling incurred before or during said crap, probably caused by the food ingested to create the aforementioned crap.

Don't go in there yet. I just dropped a bowlstainer.

bowlstainer by Mike P. Grant, Esq. May 25, 2007