When taking a dump, the feces is so large, and hard packed, that it feels as though it is scraping the walls of your anus on the way out.
Guy 1 - Dude, what the fuck were you yelling about in the washroom?
Guy 2 - I just shit out a 3 foot Wall Scraper.
A home run that barely goes I’ve the fence
Teammate: That dinger you just hit was a wall scraper