Apparently, there were commercials in the 60s and 70s for the Ty-D-Bol (Tidy Bowl) toilet cleaner brand that has a little man floating about cleaning the toilet in a little boat.

From my interpretation, this is him and his family sitting in the bowl and someone coming to take a shit, hence the “full moon.”

I had to Google it.

Ty D Bol was (is?) a toilet bowl cleaner if that helps.