The detritus of toilet paper left on the bathroom floor (or in one's clothes) after using the bathroom.
The floor of their bathroom was covered in little pieces of butt rubble and hadn't been cleaned in ages.
by Petersworld May 30, 2011
by shootingoon August 26, 2008
An unsavory looking bubble butt riddled with cellulite and having the appearance of bag of rubbles/rocks..
by Kingstonjade March 10, 2014