Green’s Dictionary of Slang

calathumpian n.

[ety. unknown; ? SE calamity + thump + play on callithumpian n.]

one who claims an imaginary religion.

[Aus]Bulletin (Sydney) 29 Sept. 10/1: The most unconsciously-humorous man in Melbourne is a converted psalm-smiter who lately referred to Sam Mauger as a ‘wowser.’ The unconscious humorist, it seems, was formerly a devoted Calathumpian with only one failure.