Ah, the humble flip-flop. Unglamorous in essence, often constructed of rubber and plastic, and costing just a couple bucks (unless you're springing for an exorbitant designer version or this $18K pair), they're ideal for poolside wear or sandy situations. Designer Christian Louboutin is actually a huge fan of 'em. But they're mired in controversy when it comes to being worn while running around the city (Jennifer Aniston doesn't seem to mind, nor does Kristen Wiig). Now, there's a new concern associated with the oft-debated footwear: Injuries, as Lena Dunham kindly brought to our attention on Instagram last night. We're not just talking about garden-variety strap chafing or inadequate arch support. Dunham ended up in a Lenox Hill hospital after stumbling over her shoes. "But seriously I tripped over my flip-flop," Dunham captioned the shot of herself looking pretty peeved and, well, flopped on a hospital bed. The snapshot shows her accompanied by a stethoscope and hospital gown to ominously underscore where one could end up simply by donning flip-flops. X-rays revealed it was a "just a stupid sprain" and Dunham said she left the ER "intact but for my pride." So, wherever you stand on the mingling of flip-flops and dirty streets, there's clearly a more pressing paranoia now involved with wearing the divisive sandals than just the potential for, oh, deadly staph infections and such.