In Pulp Fiction, what is in the briefcase?

The briefcase is a "MacGuffin" (random plot device of no relevance other than to advance the plot). There are various theories about what is in the case but none of them are the definitive answer because there simply isn't one. The contents of the briefcase can be whatever you want it to be. It's a frustrating answer for some and a brilliant conclusion to others. You an search the net for all of the theories out there, but just know that none of them are actually factual because it's totally subjective...there simply is no right or wrong answer.