So when is a nipple slip not a nipple slip? When it's stopped short by Beyonce's double-sided tape. And while her protective measure didn't quite do the full job it was meant to, it did work for about 99% of the time.
That is to say, if you look real close in this barely there nipple slip picture, you can see that Beyonce's tape is struggling to hold on to the inside of her dress, and is itself slipping off her nipple. Of course, you still can't see much at all.
So, go ahead, investigate the pictures, and wonder longingly of what might have been. You can also check out more pictures from this almost Beyonce nipple slip after the jump.