Green’s Dictionary of Slang

a billiard/snooker ball made from the synthetic ivory trade-marked Bonzaline.

1900		Referee (Sydney) 24 Jan. 10/2: If such be the case, he will find some difficulty in fixing his games up, for most of our leading cueists, with the exception of Meramatt, have an aversion to the ‘Bonzo’s’.
1910		Sydney Sportsman 31 May 2/5: There are many who conclude that if Reece strikes form, and is at home with the bonzo’s, he will secure honors, while, on the other hand, the majority pins its faith in the youthful Australian.
1912		Referee (Sydney) 1 May 14/1: [H]is intelligent manipulation of the ‘bonzo’s with his dexterous left hand proclaims him a coming champion worth watching.