Acronym for Perfect Bowel Movement; a bowel movement which vacates quickly and smoothly without the need for exertion, leaves no mess behind, requiring no wiping, and leaves the sitter satisfied.
Some believe a certain (unknown) combination of dietary habits is the key to a PBM.
1. "I'm on a journey to achieve a PBM!"
2. "PBMs are good for the environment, as they waste no toilet paper."
3. "Wow, after that PBM I feel like I can eat a whole pizza, but that may ruin the chances of a second PBM."