This is a term that was originally applied, not to clergy, but to a female with an unsightly arse. The arse in question might be fat, lopsided or saggy, it could be overly skinny or have strange looking lumps and bumps on it, or it may just not look right. Any of these attributes would turn her into a cassock wearer. It all goes back to a saying that started in England just after World War II. At that time, most people went to church and would kneel for prayers on a sort of cushion called a hassock. These hassocks could be lopsided or saggy, frequently skinny and often had strange looking lumps on them. Somebody made the comparison of an unsightly female arse to a hassock and from this grew the rhyme “with an arse like a hassock she should wear a cassock”, which was shortened to cassock wearer. It has now become a term applied generally to an unprepossessing female.
by AKACroatalin February 22, 2016
Clergyman from any number of different Christian sects who introduce young alterboys and choirboys to the mysterious inner working of the church by the secret ceremony of the lifting of the cassock.
Choirboy: The Reverend has asked me to stay behind and help him to find some coins that fell off the collection plate and rolled under the alter.
Alterboy: Don't do it, trust me dude, he's a total cassock lifter.
Alterboy: Don't do it, trust me dude, he's a total cassock lifter.
by Blue Cawdrey November 23, 2004