Secretness level: James Bond gun-barrel sequence
Secret kept for: 129 years
Before you ask, no, the secret ingredient isn't cocaine. But we can't tell you what exactly is in a can of Coke, because the ubiquitous soda has done a damn good job making mystery part of its marketing. The recipe currently sits in a vault in the World of Coca-Cola museum in Atlanta which includes features both gimmicky (fake smoke!) and legit (palm scanner!). Only two unnamed execs know it, and they're supposedly not allowed to fly on any planes together. That said, many people have claimed to uncover the cola recipe over the years. NPR published one from an old newspaper in 2011, and Mark Pendergrast printed one in his 2000 book For God, Country & Coca-Cola. Coke has of course denied that any of them are the real deal, but the cracks could be showing.
Bush's baked beans
Secretness level: Agent 13's mailbox hiding spot
Secret kept for: 46 years
In case you haven't yet heard it from that talking golden retriever Duke, Bush's prides itself on its secret family recipe. Much like the Colonel, the Bushes scatter pieces of the recipe to multiple suppliers and, just to taunt the public, they have a replica recipe book that's missing the actual recipe at their Chestnut Hill visitor center. Those are some decent moves, but Duke's bound to blab to the wrong dog one of these days.
Secretness level: Jason Bourne's Albanian passport
Secret kept for: 410 years
Because it's over four centuries old, the history of Chartreuse can get a bit muddled, but most people agree that the Carthusian brotherhood acquired the manuscript which would inspire Chartreuse in 1605. The so-called "Elixir of Long Life" was perfected in 1737, and has stayed with the monks all these years. Traditionally, only two monks know the recipe at any given time and if you've met even one monk, you know those guys aren't saying jack.