HUH?
From Lisa Russell-Pinson: “While I was an exchange student in England, I heard the phrase to take the Mickey, meaning ‘to tease’. Do you know where this expression comes from? Does it have something to do with disdain for the Irish? Is it a euphemism for to take the piss?”
It is, yes. It dates from at least the 1930s in various forms; the oldest version recorded in print, from 1935, is to take the mike out of, as in this from a book with the title Cockney Cavalcade: “He wouldn’t let Pancake ‘take the mike’ out of him”. It’s said to have its origin in the rhyming slang to take the mickey bliss, that means to take the piss. Mickey as a diminutive form of Michael has been common for many years, but how it got together with “bliss” is unknown, so we’ve no idea whether it is a reference to an Irish Mick. As the form first recorded is already elliptical, either the rhyming slang is actually older than the 1930s or some other source has to be looked for. In the 1950s a mock-genteel version to extract the Michael became briefly fashionable.