The fakey, out-of-a-box Irishness that insists on the same damned songs and the same damned menu and the same damned Guinness advertisements on the wall of every Irish bar outside of Ireland.
Seen in nearly every film which features a non Irish actor doing an Irish accent. Notable exceptions include Daniel Day Lewis in "In The Name of The Father" and Bradd Pitt in "Snatch".
"Every St.Patricks day Jose liked to emphasize his Irish roots by wearing green, drinking Guiness and referring to the 'old country' but it smacked of Paddywhackery"
When someone is a true alpha male, a physical beast and a brave passionate man who wears his heart on his sleeve. He can be given the name Paddywacker.
when you're holding up your phone and making faces at it, as though you are taking a selfie, but you're really taking a picture of the person across from you or the wall or anything else that seems interesting but you don't want to be caught dead taking a picture of.
This action is often made more convincing by wiggling the eyebrows or opening the mouth, to pretend you're trying to get a Snapchat filter to work.