Green’s Dictionary of Slang

(Aus.) a jockey.

1949		L. Glassop Lucky Palmer 190: I tell the hickey hockey to keep it at three quarter pace over six, but he can’t hold it.
1983		R. Aven-Bray Ridgey-Didge Oz Jack Lang 31: Hickey Hockey Jockey.
1999		G. Seal Lingo 142: Like other sports and gambling games, horseracing has an extensive linguistic repertoire of its own, the use of which marks out the true punter from the hordes of mug punters or amateurs [...] hickey hockey is racing rhyming slang for a jockey.
2002		Pete’s Aussie Sl. Home Page 🌐 hickey hockey: a jockey.