Apparently, there’s some confusion of the proper way to say "Reese’s," in reference to the popular peanut butter candy. It’s such a hot button issue that the argument even made its way into the latest season of "Orange is the New Black."
So, what’s the debate? Some people insist on pronouncing it “Rees-EES” as it would rhyme with “CiCi’s” despite the fact that the commercials always pronounce it “Rees-IS” as it rhymes with “pieces.” (Although those on the “Rees-EES” side seem to pronounce the candy variety “Rees-EES Piec-EESE.”)
Need confirmation? Here’s a 2017 commercial featuring audible pronunciation of the product:
Spoon University recently wrote an article about the history of the candy that gives a good explanation of why it’s pronounced the way it is. Reese’s Peanut Butter Cups were named after their founder, Harry Burnett Reese, so it’s a possessive form of his last name. It’d be the same as if you were talking about Reese Witherspoon’s movie: You’d say “Reese’s movie.”
But if you’re on Team “Rees-EES,” don’t be too devastated. The bright side is that no matter what you call it, it’ll still taste just as delicious. (But let's be clear: You're still wrong.)