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!