"Party hardy" or "party hearty"?

The NYT has a "Sunday Styles" article about sororities at Harvard. Somehow, at the NYT, the fact that something happens at Harvard is the essence of newsworthiness.

[S]ororities of the traditional state-college variety have taken root at Harvard, a place where for years the biggest social event for women was the annual Take Back the Night rally. Kappa Alpha Theta, the sorority of Laura Bush and Lynne Cheney, was the first to arrive on campus, in 1992. Delta Gamma followed in 1994, and Kappa Kappa Gamma opened its chapter in 2003. But while Harvard sororities share the same Greek letters as their party-hardy sister chapters at Michigan, Texas and Ole Miss, their social agendas are startlingly wholesome, perhaps giving new meaning to the phrase Harvard Square. They hold kickball tournaments and pajama parties and take apple-picking trips. Their recruitment meetings take place not at bars but at the local Finagle a Bagel and Au Bon Pain. And far from being catty and exclusive, they strive to welcome any woman who might hope to join.

"Party hardy"? Shouldn't it be "party hearty"? Google shows a slight edge for "party hearty" (31,800 hits) over "party hardy" (27,700), but let's check out the commentary:

Hardy/Hearty. These two words overlap somewhat, but usually the word you want is "hearty.” The standard expressions are “a hearty appetite,” “a hearty meal,” a “hearty handshake,” “a hearty welcome,” and “hearty applause." "Hardy” turns up in “hale and hardy,” but should not be substituted for "hearty” in the other expressions. “Party hearty” and “party hardy” are both common renderings of a common youth saying, but the first makes more sense.

I'll bet a lot of people haven't really noticed that these are two different words:

These two sound much alike and can easily be mistaken for each other in the spoken language. Hardy means “strong, daring, able to withstand stress” and, of plants, “able to live through the winter.” She’s a hardy person, at eighty-two still caring for her own house and garden. Hearty means “cordial, enthusiastic, unrestrained, vigorous,” as in She gave us a hearty welcome followed by an equally hearty dinner.

Well, what are you really trying to say to someone when you say "party hardy/hearty"? If you're trying to wish the person well in holding up to all that drinking, it's "hardy." If you want them to have a lot of rollicking fun, it's "hearty." If you're trying to say both, stick to the spoken word. If you're the NYT, and you mean to insult the catty, exclusionary state school girls, "hardy" actually is the better choice.