Illicitly, against regulations, of goods kept under the serving counter in a shop to be unobtrusively passed to a customer who knows they are available for surreptitious sale (e.g. pornographic magazines in a newsagent).

(Britain, Ireland, colloquial) In an underhand way, sneakily; unofficially, particularly with regard to payment or tax avoidance.

(colloquial, with regard to income) Undeclared for tax and social insurance etc.

It appears; it seems; apparently.

(Australia) A coded warning used by men to alert each other that female guests ("ducks") are present ("on the pond"), so that for politeness they should moderate their language.

Alternative form of is the Pope Catholic?

(Ireland, historical) Electoral strategy pursued by the Irish Republican movement in the 1980s and early 1990s, where elections in Northern Ireland and the Republic of Ireland were contested by Sinn Féin, while the IRA continued military operations against the British Army and RUC.

(biblical) The fifth book in the New Testament of the Bible.

(UK) At the limit of one’s patience; frustrated or annoyed.

(biblical) A deuterocanonical, apocryphal book of the Bible.