On the reddit thread Reddit Store Owners, what tricks do you use to get customers to spend more money?, kinggimped posts:
A friend of my girlfriend runs a pretty popular deli/eatery in Auckland, New Zealand. They're famous for their pies, which are made fresh right there every day.
After being open for around 6 months, they noticed that the worst-selling pie was the Mexican one. They always had at least 2 or 3 left over at the end of the day.
So, for no other reason than a social experiment to see how easy people were to influence, he renamed the pie "The Lady Gaga". Exactly the same ingredients, same location on the menu and the pie rack, just a different name.
The Lady Gaga pie now sells out first, every single day. They rarely have any left by 1pm, let alone by the time they close. He told me that when people come there for the first time, the pie they usually have is invariably the Lady Gaga.
Even though I'm a pretty cynical person and love to whine about groupthink and lowest common denominator stuff, this was still hugely surprising to me.