Just about every story told by anyone who has ever worked retail in this side of the galaxy begins with the phrase, "There was this guy…"
With it comes the unspoken understanding: Don't be that guy.
Given the way this universe works, it seems highly likely that "that guy" doesn't actually exist. Instead, what we're likely to be dealing with is a highly invasive microorganism which jumps to host to host, infecting them with a strange kind of temporary insanity that compels them to go to the nearest grocery store.