The New York Times reported last month the results of a study which claimed that obesity can "spread" like a virus, because when one person gains weight, close friends tend to gain weight, too.  I have long said that obesity has more to do with personal responsibility than happenstance; you can't gain an extra 10 pounds by being in the same room with an obese person or a bunch of cookies. 

In catching up on some summer reading, I found this hilarious (and on-point) response from Cafe Hayek's Russell Roberts:

"The real lesson here is that if you see your best friend gaining weight, stop being friends with your best friend. Dump your fat friends. You don't want to catch the obesity 'virus.' In fact, make friends with people who are thinner than you. What a great study. All those people who judge people on their looks were right after all! It turns out that looking for thin, fashionable friends is actually good for you."