Signs and the Wrong Type of Persuasion
Confessions of an Efficiency Nazi: I hate it when people want to try flavors in ice cream, gelati and yoghurt stores before they buy. Especially when there are a lot of people waiting. It’s a $5 purchase people. Wanna take a guess at what banana flavored ice cream tastes like?
My favorite gelato place decided to help this problem by explicitly stating that you could only try 2 flavors. They installed this sign.

Except, anecdotally, I think it backfired. It seemed to have created more tasting. It’s given everyone permission to taste. When people see the sign, what they read is “Please taste 2 flavors before buying”.