The act of immediately bathing after taking a dump. This can be done out of convenience (getting ready in the morning as part of a normal routine) or necessity (little to no toilet paper or just a plain messy dump).
If the shower is initiated before the dump it can also serve to mask common noises heard during the act including, but not limited to grunting, squeaking, banging, moaning, plopping, and echoes.
The term rolling is figurative and not literal. There have been no known cases of an individual physically rolling from the toilet into the shower.
"After downing 2 bowls of my mom's chili, I knew Alex was going in for a rolling dump because the shower started right after he sprinted into the bathroom"