Saw this on Kotaku, NSFW I supposed. Skip to 1:55 on the video to actually see the "evidence".
Taking a quick glance at the game's ESRB rating, it definitely doesn't say anything about nudity in the game, but given the games love of face dead zombie girls and camel toes, it's probably not too surprising.
Most people are saying the vaguely vulva-esque looking piece of character model is actually just the legs coming together in that angle, the question is if when inevitably the ESRB is informed of this video, if they will force the game to be pulled and re-print the discs. Is this hot coffee part 2? Will I get a $5.00 check from Dead Island devs five years from now?