To flip someone off in Ireland and the UK, you make the V-sign and hold it out palm inwards. Usually, the index and middle finger are closer together than, say, in the gesture you would make ordering two gyros at the falafel truck.
This version of the bird ("the two-fingered salute" as they call it) was designed and put into order by Parliament specifically and for no other reason than to enable Shane MacGowan to flip you off every time he takes a drag from his cigarette on stage. It's a fact.
