Doppelgänger, German for "double-goer" or "double-walker," is an apparition of oneself, either real or ghostly, though the word is now also used to mean alter-ego, mirror image, or a gothic twinning. Doppelgänger week is an internet meme in which users of social networking websites change their profile picture to that of celebrities, athletes, historical figures, or friends with whom they share a physical resemblance. Does your piggy have a doppelpigger? Do you?<br><br> #guineapigdoubletrouble <br><br> Photo: courtesy of Jackie's Guinea Pigs