Apple,
Since you and others got the quote, and I promised to explain, here goes:
It’s based, I think on British slang.
“It’s crackers” - means It is foolish, or crazy or stupid.
“a rozzer” is a policeman, or an authority figure.
“dropsy” means a bribe, or a payoff.
“snide” means counterfeit false cash.
Thus, the quote means
“It is foolish to attempt to bribe a policeman with counterfeit money” - sound advice, I would think.
Don’t bring the Pommies into this, that quote is dinky di Aussie, mate.