"That's WRONG," they proclaim. "Patty is a girl's name. The short version of Patrick is 'Paddy'!"
Drives 'em nuts.
Since it's unlikely that anything's going to change over here (and let's face it, they already have that John -> Jack, Edward -> Teddy thing), I propose a compromise:
Let's split the difference, and call it "St. Patdy's Day."
("St. Padty's Day" would also work.)
That way, no one's happy.