Police investigate the scene of a shooting at 75th Street and Stewart Avenue on Saturday in Chicago. At least 50 people were shot in the city, nine of them fatally, in a wave of violence over the Fourth of July weekend. E. Jason Wambsgans/MCT /Landov hide caption

itoggle caption E. Jason Wambsgans/MCT /Landov

There are signs around the reservoirs in Portland's Mount Tabor Park that warn against putting anything in the water. They apparently didn't dissuade one young man from urinating into the city's drinking supply this week. Randy L. Rasmussen /The Oregonian/Landov hide caption

itoggle caption Randy L. Rasmussen /The Oregonian/Landov

"Too darn funny what a co-worker put on top of her lunch. It was fake of course, but got the point across." Courtesy of Toni Kinnard hide caption

itoggle caption Courtesy of Toni Kinnard

One of the world's rarest flowers has been stolen, Britain's Kew Gardens announced this week. The water lily Nymphaea thermarum is seen here in 2010. Andrew McRobb/AP hide caption

itoggle caption Andrew McRobb/AP

Eugen Darie has admitted to being part of a Romanian gang that stole seven works by masters including Pablo Picasso and Henri Matisse from a Rotterdam museum last October. Vadim Ghirda/AP hide caption

itoggle caption Vadim Ghirda/AP

When researchers at Weill Cornell Medical College scanned teenage brains, they found that the area that regulates emotional responses has to work harder to keep impulses in check. Courtesty Kristina Caudle/Developmental Neuroscience hide caption

itoggle caption Courtesty Kristina Caudle/Developmental Neuroscience