extra-curricular

   referring to taboo extramarital activity

   Literally, anything at school, college, etc. which is done in addition to the prescribed course of study:

    Though industry pundits reckon Halpern — better known for his exuberant extracurricular activities — itches to get back in the high street. {Sunday Telegraph, 5 June 2001 — he had, when chairman of a multiple retailer, seen the details of his oftrepeated sexual activity with a young woman become public knowledge)