Ben & Jerry’s is a quirky but wildly successful ice cream company, renowned for its offbeat marketing and for donating a portion of its profits to good causes. Two lifelong friends, Ben Cohen and Jerry Greenfield, started the company in a converted gas station in Vermont with nothing but $12,000 and a great sense of humor. Over the years, Ben and Jerry created the world’s largest ice cream sundae (more than 13 tons!), launched their famous Cowmobile (a converted motor home that handed out free scoops of Ben & Jerry’s across the country), delivered a 900-pound baked Alaska to the U.S. Capitol Building, and raised millions of dollars for community action causes through their foundation. Since most of us spend a third of our lives at work, Ben and Jerry reasoned that work should be both fun and a positive force for good.

Year after year, Southwest Airlines achieves some of the lowest employee turnover and the highest customer satisfaction rates in the airline industry. Here are some of the maxims that guide the company’s approach to business:

Hire people with a sense of humor

Encourage people to adopt a playful attitude

Be the first to laugh

laugh with, not at

Take work seriously, but not yourself.