John Lennon knew he could get by “With a Little Help From My Friends,” and while some friends you can’ t live without, there are others that just aren’ t worth having. In contemporary lingo, these unfriendly friends have been deemed “frenemies.”

A frenemy is an enemy disguised as a friend. One who brings you down rather than lifting you up. The kind of girl (or guy) who won’ t rescue you from a bad blind date. The type of pal who makes himself or herself feel better by constantly putting you down.

Sunday marks National Friendship Day as proclaimed by the U.S. Congress in 1935, and what better time for two New York City authors and real-life friends to release their latest book, “Friend or Frenemy? A Guide to the Friends You Need and the Ones You Don’ t.”

Andrea Lavinthal, an editor at Cosmopolitan magazine, and Jessica Rozler, who works in book publishing, are very different women who offer a very real perspective of what makes a good friend, how to get rid of your worst frenemies, and who should make it into your framily (aka friend-family).

“Like John Travolta’ s hair, some friends seem genuine at first, but upon closer inspection, they turn out to be high-quality fakes,” they write in advance of the Friend or Frenemy quiz — one of the most valuable sections of the book (see page 109).

Not only do the authors offer advice, there also are interactive portions where you can question yourself, your friends and perhaps your frenemies. The book serves as a guide to friendship and includes advice, explanations, illustrations and even helpful diagrams on what makes a strong friendship.

Hilariously funny but also astonishingly true, they tell it exactly how it is using examples any gal (and most guys) can relate to.

The authors aren’ t new to the world of published writers. In fact, their last publication, “The Hookup Handbook: A Single Girl’ s Guide to Living It Up,” went on to be released in nine languages and was covered nationally by major print and television media.

Their latest likely will rank right up there as well.

The ladies take a look at friendship in today’ s fast-paced technological world and the way relationships can be formed without ever meeting face-to-face. While not useless (in fact, the authors agree that cell phones and “CrackBerries” can be very helpful in communicating), Lavinthal and Rozler note that there’ s nothing like sitting down with a good cup of coffee or bottle of wine and talking to another person.

Then there are The Friend Commandments — rules to live by that include never making your friend wear green taffeta or allowing her to leave the house wearing Crocs unless she works at a hospital or a garden.

The story of these ladies wouldn’ t be complete without adding a touch of style to their latest book. Jewelry designer Adnia Reyter, a minimalist with class, designed a spinoff of a friendship classic in honor of “Friend or Frenemy.”

Young girls often don friendship bracelets braided during sleepovers from bits of cross-stitching thread found at the bottom of sewing drawers. A fancier version of this friendship tradition is the single necklace that can be split in two — one side saying “best,” the other “friends.” Friends would split them up and wear them to symbolize their friendly bond.

Reyter has taken that tradition and made it classy. Yes, that’ s right. Even grown women will want this upscale- version “Best Friends” twisted heart necklace available in silver and gold.

At $135 in silver or $675 in 10-karat gold it’ s a little pricier than the dollar-store version most were used to as children, but also much classier.

Lavinthal and Rozler also have designed T-shirts in honor of the book with friendly sayings that are being sold at At about $21 they’ re very cute and 20 percent of the proceeds is donated to the Best Friends Animals Society.

The book is available at most bookstores, including Barnes and Noble and Borders, and online at Amazon.