a man’s habit of sexual promiscuity or infidelity—refers to the zipper on the flies of a pair of trousers—USA, 1982, originally used of Members of Congress in Washington, D.C., and recorded by gossip columnist Diana McLellan
UK, 1803, as an adjective—UK, 1842, as a noun—in reference to the action or practice of attacking, or acting against, someone in a treacherous or underhand manner
Ireland, 1914—the action or practice of attacking, or acting against, someone in a candid or open manner, as opposed to deceptively or duplicitously—coined after ‘backstabbing’ (i.e., the action or practice of attacking, or acting against, someone in a treacherous or underhand manner)
chiefly UK politics—a culture characterised by influential networks of close friends—from ‘chum’ (a close friend) and ‘‑ocracy’ (forming nouns designating forms of government or groups who exercise political or social power)
USA, 1826, as ‘to flog somebody like seven bells’—to give a severe beating to somebody—‘seven’ is perhaps simply an arbitrary intensifier—cf. phrases such as ‘like seven bells half-struck’ (‘with as much speed as possible’) and ‘to blow seven bells’ (‘to blow a violent gale’)
a person who covertly exercises power by personal influence over a ruler or government without having any formal authority—ascribed to William Pitt the Elder by William Godwin in 1783
1815—inner ruthlessness and determination disguised in outward gentleness and courtesy—loan translation from French ‘une main de fer dans un gant de velours’ (1814)