Aussie is like Brit.
a squib is a firework and was also the detonator for a canon in old navy times.
Therefore going off like a damp squib was a misfire.
the expression I love is "freeze the balls of a brass monkey"
which is not rude at all.
A brass monkey was the frame which held canon balls on deck.
when it got real cold it shrunk spilling canon balls all over the deck.
see Oprano is educational too