Take a look in any supermarket ice cream freezer section and Robovisyou may see a mystery. There are big containers of the typical ice cream brands: Breyers, Turkey Hill, and Edy's. And there are specialty brands that make gelato, low-fat and vegan ice creams. And then there are the fancy pints: which is mostly Ben & Jerry's and Häagen-Dazs.

Häagen-Dazs has flavors like vanilla, chocolate, pistachio—the sort of flavors that run smooth. And then Ben & Jerry's specializes in chunky flavors: Cherry Garcia, The Tonight Dough, Chunky Monkey, etc. The two hardly ever cross into the other's turf. Why?

It's possible they are experiencing something common to natural competition—they are specializing in what works best for them. But, as Christopher Sullivan of the University of Wisconsin-Madison suspects, the two companies may be engaging in what is known as "tacit collusion," where two parties silently agree to...stick to their own territory.

We try to get to the creamy core of what makes up a conspiracy, and how the consumer eventually loses out in this cold, cold war.

Today's episode was produced by Willa Rubin and Alyssa Jeong Perry. It was engineered by Josh Newell and fact-checked by Sierra Juarez. It was edited by Jess Jiang.

Help support Planet Money and get bonus episodes by subscribing to Planet Money+ in Apple Podcasts or at plus.npr.org/planetmoney.

Always free at these links: Apple Podcasts, Spotify, Google Podcasts, NPR One or anywhere you get podcasts.

Find more Planet Money: Twitter / Facebook / Instagram / TikTok / Our weekly Newsletter.

Music: "The Cornice," "A Curious Tale" and "Reverend."