[rsynnott]

> Your linked term comes from an acronym written on prison cell doors (Not On Normal Courtyard Exercise)

These are _always_ backronyms. _Always_. If anyone ever tells you that [random word that's been around for a while] is an acronym, they are _wrong_. (Possible notable exception for 'fubar'; that one's old enough now and probably really is an acronym).

[kevindamm]

Yeah I shouldn't have assumed that was right, even if it seemed more likely than "nonsense" and especially since I'm not very familiar with UK slang.

It seems the exception is those terms with origins in military and academia.