jag, n.
NO SOONER has John Redwood derided John Prescott as "two Jags" than I am possessed of one. That is to say, I am on a painting jag (walls, not flowers, fruit or soup-cans), and another instance of our using a word while being unsure of its origins.

Nineteenth-century Amer-ican, earlier than the OED's first citation (Jack London), this sense of a fit of activity derives from our 17th-century slang for as much drink as one can handle, itself a variant upon the earlier sense of load or burden, whose origins are as obscure as that for piercing protruberance (jagged edge - perhaps onamatopoeic).

The motor-car had become shorthand for vulgarity by the late Fifties, soon augmented in the phrase "gin-and-Jag". As for me, it's time not for a gin jag but the tang of turps. Ah!