Green’s Dictionary of Slang

sices n.

[14C SE sice, the six on a die]

in dice-playing, a throw of six.

[UK]Hotten Dict. of Modern Sl. etc.
[UK]Hotten Sl. Dict.
[Aus]Sydney Sl. Dict. (2 edn) 8: Sices (or Sizes) - A throw of sixes at dice.