A small, individual, rounded piece of shit not large enough to be a proper turd. These are usually not larger than peanut M&M's.

A person (usually male) who lacks guts and determination.
When faced with a crisis, a pebble gut will either run away or cry.

Coined by the big wall Yosemite climbers of the late 70s and early 80s, a pebble wrestler is a boulderer that appears to be "wrestling pebbles" from the view from Yosemite's Half Dome or El Capitan.

A project rooftop. Usually the rooftop is only called "Pebble Beach" when a sexual encounter has taken place on said rooftop.

the space underneath the shaft of the dick and the ball sack

Inadvertant output of solid matter when attempting gasseous release.

The effect of the violent purging of liquid shit from the back passage, which leaves a 'splattering' of crap on the back of the toilet bowl, not dissimilar from a type of exterior wall coating.

For maximum effect the 'pebble dasher' requires a significant amount of 'wind' in their system and must strain hard whilst simultaneous holding their ring piece closed (with hands if required). Once enough pressure has built up the opening of the ring piece will allow the pebble dashing to occur.

Pebble dashers should note that one school of thought maintains that given extreme straining, the material exiting the rear can potentially achieve super sonic velocities, momentarily creating a shock wave that can tear the ring piece. Their advice is therefore not to strain too hard!