The mysterious and undetected figure responsible for fouling public toilets (including those in the work place) in a most heinous manner. To Crimp in the modern vernacular being the verb to open one's bowels. In these cases the faeces usually manifests itself on the rear side of the toilet seat. Using complex trigonometry and huge amounts of conjecture, scientists have hypothesised that a human sub-species possessing an Anus in the lower back is responsible.
Jenkins: By jings Frobisher! Some poor fellow has made a deeply unsuccessful attempt at dropping night soil in this Privy.
Frobisher: Jenkins you bloody fool! Can't you see? This is obviously the work of the Scarlet Crimpernel. Call the Gendarmes!