On Twitter, @paddynotpatty has had a merry time of it pointing out that the diminutive of St. Patrick is St. Paddy, from the Irish name Padraig, insisting that "St. Patty" is simply wrong. Well, actually, that's only half the fun. The other half has been retweeting the ignorant comments of Americans.
The responses tend to follow the pattern of "His name is Patrick, not Padrick." Of course, since he was a Romano-Briton (and not Irish), if you had asked him what his name was, he would have said Patricius.* "Patrick" is modern English. Old English would have been "Patric," but in Ireland he would most definitely have been Padraig, hence "Paddy" to anyone presuming to be on familiar terms with him.
Some of the tweets have the belligerent tone characteristic of Internet discourse, along the lines of "This is AMERICA, and we call him Patty," with an intensive for emphasis that I shan't reproduce here. Militant ignorance, not one of our more attractive national characteristics, has been on wide display. Made by God as ignoramuses, like all of us, some of us appear not to have bestirred themselves to improve on the original product**