It appears to be a pastie. Showgirls, strippers, soccer mom's (that wsa for you James), wear them to cover their nipples when their breasts are exposed. You can purchase them over the internet or at various adult shops such as:
http://www.twirlygirl.net/.
I can not imagine that anyone thinks the performance was not planned. They had to do something to make the halftime show entertaining (if that is what you would call it)... that was possibly the WORST show I have seen. The stars for the preshow and Beyonce singing the national anthem was much better. They were in Texas, it is too bad they did not have country music stars during halftime and not just pregame! And what 18 year old has heard of Janet Jackson... and no 40 year old cares about Justin except his mom. IMO: It appeared that MTV through the show together at the LAST MINUTE!!!!!!!!!!!!