We've all walked into a screen or door we didn't see. Embarrassment sets in quickly, but while the pain takes your mind off that feeling, you start to realize that if you had seen someone else walk smack into the glass, you'd be rolling on your sides laughing as well. Even Justin Beiber has been caught on camera (a few times, it seems) crashing into a plate of glass! Goes to show that no one is immune! It can happen to birds and dog, cats and kids, just about any living thing with eyes can be fooled by a very clean window. Watch out, keep your head up, your eyes peeled, and don't be one of these hilarious people who walk smack into glass doors!