As Justin Timberlake sang the "gonna have you nekkid by the end of this song" line during a duet of "Rock Your Body" with Janet Jackson, millions of viewers had no idea that he actually planned to deliver on that promise.
He then removed a piece of Jackson's outfit that exposed her bare breast (well, bare except for that weird metal sunshine ray thing around her nipple). She feigned surprise and embarrassment and quickly covered up her boob, and then the world reacted.
In this reporter's opinion, the event should have been referred to as Super Boob Sunday, but some uncreative somebody somewhere added a "gate" to the word "nipple" a la Watergate, and thus it was dubbed Nipplegate.
Publicists quickly rushed to explain that it was a "wardrobe malfunction," which always seemed like a big fat "I didn't inhale." It was an excuse so ridiculous that it mocked those who were angry about a woman exposing something that a man can expose any old time. Good move, PR!
Luckily, this year, when Red Hot Chili Peppers joined Bruno Mars during the Super Bowl halftime show, when they revealed their nipples, it wasn't the most offensive part of the performance. We've come a long way, baby.