Some people want to save the trees. Other people, whales. For Jerry Benzl, 30, it’s the United logo. Benzl is a Ph.D student in PolySci in Laguna Beach, Calif. He’s also very unhappy United is planning to put Continental’s globe-shaped logo on its planes after their merger. So he joined a group on Facebook — “Save the United Tulip.”

“It’s sort of like someone, you know, getting a face transplant,” he says.

Creepy. Except a logo isn’t a person, it’s a corporate symbol.

“Symbols have always been important. Nations have flags, religious symbols. It makes sense in this age where corporations have such a big presence in our lives that the symbol for that corporation begins to mean something.”

And Benzl says it does mean something — to him. He feels proud to be a customer. The airline is one of the country’s oldest.

“I’m almost embarrassed to say, but it’s like these warm tingly emotions,” he says.

People get emotionally attached to brands. But why?

“It’s not just about a product, it’s about a brand that has a role in my life and the associations around it,” says Tim Calkins, who teaches marketing at the Kellogg School of Management.

Examples include the orange juice you had on your first day of school. Or the airline you flew on your honeymoon. If you pair a brand with an experience, even everyday products can take on a lot of meaning. But when consumers care brands have to be careful.

Calkins told me about one misstep when department store Macy’s was buying up lots of small regional chains: “When they changed the branding to Macy’s, the change was fine.”

Macy’s would gradually fade out the old name while their own name slowly got bigger. Until the retailer got to Chicago and the Windy City’s beloved Marshall Fields. In September 2006 Macy’s changed the signs overnight. Calkins says even now there’s groups in Chicago that continue to protest that change. He says there’s a lesson here for United and other brands: Take it slow or run the risk of turning off loyal customers.