Not for the squeamish. At first glance, it seems improbable and downright impossible, but inmates are actually attempting to stand out from the crowd by having ink injected into the whites of their eyes. DamnCoolPics has a bit more information on the procedure:
Because the we had trouble getting the ink under the surface (and were able to “wash” it out of the small needle incisions), we tried the second procedure, on Josh using a 29ga needle and syringe, thinning down the ink very slightly with an antibiotic eyewash. Since the goal was simply to blanket the white of the eye in color, there wasn’t a need for fine detail. The first injection was shallow and appeared to dissipate on the surface, but the second injection was at the perfect level and formed a dark bubble of ink just over the sclera (in the third picture you can see some of the ink running back out of the injection hole).
Link. (via Cynical-C)