I don't think it was a big deal with Janet and her boob. It wasn't a publicity stunt, it was Janet. She's been pushing the envelope for years but she's just so sweet looking people don't really notice it!
Also, I've danced in many a concert. Even in college when the budget was low, our costumes were designed/sewn to NOT fall off, no matter what. And costumes for major productions like that are fitted precisely to the performer. There is no way that was a "costume malfunction".
On another note - favorite commercial:
The donkey who became a Budweiser Clydsedale! Loved his "extensions"!