a policeman ...1938 Aust. sl.
a contraction of John Hop (a male police officer [rhyming slang for 'cop'])
FIRST DOCUMENTED USE
1938 - see EXAMPLE below
"...Anyway, a sneakin' coot of a police-boy stationed at the the Compound got to hear of it and told the jonnops. You see, at the Compound, they was callin' this lubra Missus Constantinople, same's they do when a lubra's got a whiteman playin' round with her, y' know. Well, the jonnops come along..."
- Xavier Herbert