The build-to-order burger chain has become one of the fastest growing franchises in the country, even while refusing to deliver or advertise. Check out what else has made this family company such a delicious success.

1. FUNDING FOR THE FIRST FIVE GUYS CAME FROM A COLLEGE SAVINGS ACCOUNT.

Five Guys' initial $70,000 in startup funds was meant to pay college tuition for Jerry and Janie Murrell's (at the time) four sons. They sensed their oldest children were on the fence about heading off to college, and the pair offered an alternative in 1986: using the tuition money to launch a family burger joint. Jerry Murrell, who now acts as Five Guys' CEO, has said the idea was about keeping his family together. "They weren't scholars ... I always liked having my kids around me, so I thought that was a good way to do it." That same year, the family launched the first Five Guys location in Arlington, Virginia.

2. THERE ARE REALLY SIX GUYS, NOT FIVE.

When the first Five Guys launched, Jerry Murrell and his four sons—Jim, Matt, Chad and Ben—made up the restaurant's namesake. But a year after opening for business, another son, Tyler, was born into the family. Jerry Murrell now says the Five Guys name references only his sons.

3. HAVE A PEANUT ALLERGY? FIVE GUYS IS YOUR WORST NIGHTMARE.

Five Guys fries all its food with 100% peanut oil, and offers complimentary bins of peanuts for customers to snack on while waiting for their order to come up. Five Guys does acknowledge its peanut-laden atmosphere with labels on its doors and asks customers to keep nuts within the restaurant to prevent causing possible reactions outside its doors. 

4. FIVE GUYS HOLDS FAST TO ITS 'NO DELIVERY' RULE—EVEN WITH THE PENTAGON. AND THE PRESIDENT.

Pentagon officials once called in a 15-burger order, expecting delivery. When Five Guys staff responded that the restaurant didn't deliver, Jerry Murrell received a direct phone call from a Pentagon higher up, contesting the restaurant policy. Five Guys took extra steps to ensure everyone knew about its "no delivery" provision: "Matt and I got a 22-foot-long banner that said ABSOLUTELY NO DELIVERY and hung it in front of our store. And then our business from the Pentagon picked up," Murrell said

5. MILKSHAKES AREN'T A STANDARD SIDE.

That's because (most) Five Guys restaurants don't have freezers due to the company's focus on fresh ingredients. Jerry Murrell said customers often ask about the menu addition, and with some push, Five Guys began testing milkshakes at some of its East Coast restaurants in 2014. Within the past year, milkshake test locations have spread to Five Guys locations in 37 states and Washington D.C.

6. THE 'SECRET HACK' MENU IS ALL ABOUT CHEESE.

While Five Guys is all about building a custom burger or hotdog, you can't get certain supposed 'secret menu' items at all locations. Double grilled cheese burgers and cheese fries aren't on the standard menu, but some locations are willing to put them together for you. Other locations won't honor the order, but you can make your dietary dreams come true by ordering the components and putting them together yourself. 

7. THE MURRELL FAMILY INITIALLY BUTTED HEADS ABOUT FRANCHISING.

The Five Guys chain is considered one of the fastest growing U.S. franchises—even extending into Canada and London. But, the idea of creating a chain wasn't well accepted among the family. Jerry Murrell said he was against a Five Guys franchise, and that his family successfully launched the chain with him "kicking and screaming." Apparently, Murrell family disagreements can get rowdy, so the Five Guys office features a soundproof meeting room to keep arguments contained. 

8. SHAQ OWNS 155 FIVE GUYS LOCATIONS.

In 2013, the former basketball player told an NCAA convention crowd that one of his main business investments included 155 Five Guys restaurants—that's 10 percent of all franchise locations.

9. FIVE GUYS TAKES ITS MAYO SERIOUSLY.

During product taste testing, the Five Guys family tried 16 kinds of mayonnaise before deciding on the right kind. Each location uses the same mayo—and all ingredients for that matter, down to bread that's baked fresh daily and trucked or flown to nearby restaurants.

10. A YOUTUBE VLOGGER LANDED HIS OWN TV SHOW BECAUSE OF HIS FIVE GUYS REVIEW.

Fast food reviewer Daymon Patterson, known online as Daym Drops, struck greasy gold with a review of Five Guys burgers. His 2012 video description of a Five Guys meal ("You bite the fry, the fry bites back!") landed him a Travel channel show highlighting fast food restaurants around the country. "Best Daym Takeout" lasted six episodes before being canceled.

11. CEO JERRY MURRELL'S FAVORITE BURGER IS PRETTY PLAIN.

You'd think the patriarch of Five Guys would have an all-out custom favorite, but Jerry Murrell's burger of choice is as tame as it gets: a plain cheeseburger. Out of the restaurant's 250,000 ways to make a burger, he'll sometimes spring for a plain burger with ketchup and mustard. But that's the beauty of having a built-to-order burger—there's no wrong way to order it.