"The picture you're looking at above isn't of just any Happy Meal. It's a Happy Meal that's an entire year old. Yup, author Joann Bruso decided to undertake a little experiment with McDonald's most recognizable icon (besides that bizarre man-clown, that is). So she bought a Happy Meal, took out the hamburger, and plopped down in her office. For a year. This is what happened."
You can read the rest of the brief article and find a link to Bruso's web site here. You can read Bruso's "Happy Meal Blog" here, although you may have to try several times: according to the blog, "My Happy Meal posting went viral with multiple blogs and news sites picking it up. The Baby Bites’ site is having a hard time handling all the hits. We are working on this issue. If you experience difficulty on the site or do not see your comment posted, please check back."
It's worth noting that several people who commented on Bruso's post report similar (usually accidental) experiments with other processed foods. One reader tells of an open "Lunchable" that sat unchanged in her kitchen for several months. Another describes how her young daughter left an uneaten Dairy Queen ice cream cone sitting in her closet for two weeks: "I was hanging up some clothes in her room [and] I noticed a perfect looking unmelted ice cream cone." Apparently the so-called ice cream shrank slightly during that time, but there was no melting and none of the foul odor you'd expect from dairy products gone rancid.
Of course none of these are scientific experiments, but they do make me uneasy!