There’s just one problem: In-N-Out policy forbids restaurants from serving anything larger than a 4×4. The rule went into effect soon after unappetizing photos of the infamous 100×100 circulated around the Internet a few years back.

What makes this oversight particularly puzzling is that Stacy Perman, who literally wrote the book on In-N-Out, works at BusinessWeek. That got us thinking: Had the 4×4 rule been dropped? Could it have just been a rumor all along? Was there really no limit to the stack of cheesy meat we could order, aside from our wallet and our imagination?

We called up In-N-Out to get the answer. Sadly, it’s true: A 4×4 is biggest you can get. Perhaps BusinessWeek should add a “some assembly required” note in its gallery, because the only way you’re getting a 20×20 is by ordering five 4x4s and building it yourself.

Update: If you’re curious what it’s like to consume such a colossal cheeseburger, Eric Albertoni ate one in 2005 and lived to blog about it.

FORA.tv has a great video of BusinessWeek writer Stacy Perman discussing her book “In-N-Out Burger: A Behind-the-Counter Look at the Fast-Food Chain That Breaks All the Rules” at Books Inc. in Mountain View, Calif., last week.

Over the course of the talk, Perman reveals how she was inspired to write the book, gives a thorough summary of the chain’s history, and takes questions from the audience. It’s packed with great In-N-Out trivia and definitely worth watching, especially if you’re too lazy or cheap to read the book. And although the video is nearly an hour long, don’t worry — FORA.tv has chopped it up into bite-size chapters for you.

In-N-Out Burger: Stacy Perman [FORA.tv]

Cool Hunting executive editor Evan Orensten recently got to test-drive the sexy Ferrari California from San Diego to Santa Monica (um, how do we sign up for that gig?), making stops along the way in Borrego Springs, Malibu, and, of course, In-N-Out:

By the time we hit Palm Desert it was nearly 120°, and after our Double Doubles (it’s not a real California until it proudly wears an In-N-Out sticker) we put the top up and cranked the air conditioning until we made our way down Mulholland Drive.

No word on how the cup holders performed, but we can’t think of anything better than cruising around SoCal in a convertible Italian sports car with a Double-Double. Check out the full review over at Cool Hunting.

Matthew E. May — Pepperdine Business School professor and author of the books “In Pursuit of Elegance: Why the Best Ideas Have Something Missing” and “The Elegant Solution: Toyota’s Formula for Mastering Innovation” — praises In-N-Out in the latest LeanBlog.org video podcast.

May uses the infamous fade-to-black ending of “The Sopranos” to illustrate the notion of how “what isn’t there can sometimes be more powerful and trump what is there” and then goes on to claim In-N-Out’s secret menu and slow expansion work the same way.

Check out the video above. The In-N-Out talk begins around four minutes in.

Chadder’s, the tiny Utah burger chain that In-N-Out sued in 2007, may look a lot like everybody’s favorite restaurant — the menu is practically identical, and so is the decor — but it’s actually more expensive and less tasty, Rhombus Magazine found:

There was a bun, meat, cheese, onions, lettuce and tomato, which combined to make a marginally tasty burger. The meat patties were a lot smaller than expected, but when you are dealing with a knock-off you learn to expect to be unimpressed. …

The fries were just like those of In-N-Out except smaller and not as crisp. …

Chadder’s is a shoddy clone of In-N-Out. Do I recommend that you eat there? If the word “cliché” describes your lifestyle, then yes, go for it. If you really want a good original burger, then don’t.”

Read the entire review to see the writer’s take on founder Chad Stubbs’ weak explanation for why he opened the wannabe In-N-Outs.

Blogger Ethan Wims is on his way to Iraq with the U.S. Air Force, but before he left, there was just one thing he absolutely had to do: Eat the last In-N-Out cheeseburger he’d see for at least the next six months.

So … I had my last meal in the states. What better way than to have the good all-American cheeseburger? There is a better way you say? Why yes … how could I forget … In-N-Out!!!

The only problem is that the malaria pills that I have to take make my stomach ache, so I couldn’t finish my fries. But I had it and it was delicious and I can’t wait to have my favorite burger joint again.

Stay safe over there, Ethan! We’d ship you a burger, but it probably wouldn’t be very good by the time it arrived.

Keep an eye out for Mayer’s next single, “Your Burger Is a Wonderland.”

Confirming what we already knew, voters in the 2009 Zagat Fast-Food Survey ranked In-N-Out tops in the nation for hamburgers.

Despite having just 232 stores spread across only four states, the tiny chain beat out #2 Wendy’s, the world’s third largest hamburger chain, with nearly 7,000 locations. Rounding out the top five were Burger King, McDonald’s and Whataburger. In-N-Out also came in first in the categories of top food and top service when compared against other chains with less than 5,000 locations.

Visit Zagat.com for a complete breakdown of the survey’s results.

Actor Hank Azaria, best known for his voice work on “The Simpsons” (Apu, Moe, Chief Wiggum and more), recently spoke to People magazine about his pregnant girlfriend’s top craving, and it’s:

(Pardon us while we mangle one of Comic Book Guy’s trademark lines.)

The best … hamburgers … ever.

That’s right, In-N-Out.

OK, so maybe our headline should say Azaria loves delivering In-N-Out, but we’re gonna go out on a pretty sturdy limb and assume he’s ordering up some of that deliciousness for himself, too, while he’s at it.

“They should really give us a year’s worth,” Azaria said on the red carpet at last week’s “Star Trek” premiere. “We are the greatest [customers]. I literally bought a hat because I’ve delivered so much In-N-Out Burger in the last six months.”

When People‘s reporter suggested Azaria go ahead and just rent one of In-N-Out’s portable cookout trailers for his girlfriend, Katie Wright, he quipped, “I might end up just buying one and driving one. That would save a lot of time.”

The Food Network has just published its list of the best hamburgers in each state, and although many of the entrees are of the gourmet (read: expensive) variety — such as New Jersey’s $16 Stage Left “Best Cheeseburger in the World” — the $3 In-N-Out Double-Double takes the crown for the Golden State.

The Double-Double wasn’t the cheapest burger on the list, though. Mississippi’s White Trolley Cafe serves an 85 cent “Slugburger” deemed worthy of recognition.

Tipping the scales in terms of price and size is West Virginia’s $50, 10 lb. “Doublewide” burger served at Hillbilly Hot Dogs. The meaty monster is served on a 25 inch bun with 35 slices of cheese and takes 45 minutes to cook.