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A shit so large, it rips one or more of the circular muscles in the anus on its way out. This usually causes bleeding and mild to intense discomfort.
Male 1 (In the restroom): Call an ambulance!
Male 2: Why?
Male 1: I just had a sphincter-buster! My anus is bleeding and I cant sit down!
by BobotheClown January 06, 2007

Words related to sphincter-buster

anus buster o-ring poop shit sphincter