I'm almost afraid to ask but what the heck... Which "nip" are we referring to?
You mean left or right?
Tara Reid was at some red carpet event wearing a low cut dress with a stole over her shoulders. When she walked up to the area with all the photographers she dramatically dropped the stole. Well, along with the stole she dropped one of the staps of her dress exposing her breast.
She's just standing there smiling, breast flapping in the breeze while the photogs are going crazy snapping her picture. Someone came up and whispered, "Hey, dummy, your boob is out," and she pulled up her strap.
I'm sure this is a pretty sturdy limb to go out on, but I always thought it was a PR stunt. How can you not realize your dress FELL OFF. Equally plausible is that she was just so hammered she didn't realize what was going on.
If I'm not mistaken, this is a reference to a "wardrobe malfunction" she had at one of the award shoes where her revealing dress slipped and revealed one of her breasts - nips and all.