In-N-Out Burger takes on bizarre threat to its popular brand

In-N-Out Burger was the first drive-thru hamburger stand in California when it opened its doors in 1948. Today, the menu is largely the same, although its famous Double-Double burger was not added to the menu until 1963.

In-N-Out has a huge following, with fans loving its “secret” menu, including Animal Style burgers cooked in mustard with extra spread, pickles, and grilled onions.  

And speculation abounds regarding what's in the company’s special spread.