A turd so large and hard that it resists repeated efforts to flush it down.
"Mom, the toilet is plugged up again; Grandpa must have had another none of his flushbusters.
A neophyte. An inexperienced person or a beginner. To be compared to a baby that kicks it's legs during diaper changes and gets shit on it's heels.
That new guy on the job is just a shitheel.