While partaking in the insuffolation of a controlled substance as a group, that rude individual who mercilessly snorts up way more than their fair portion, leaving the remaining participants with very little to enjoy.
"Well..there was plenty on the plate, until snuffleupagus here had to show us how it's done."
When you take a man and turn him upside down placing his legs over your shoulders placing his penis above your chin like a snuffleupagus- Hence the Name Walking Snuffleupagus.