Pop icon Britney Spears made a surprise appearance on The Tonight Show Starring Jimmy Fallon this week, joining the host for a session of Pros and Cons. This time, he was judging the ups and downs of dating the newly-single Spears. I'm just going to be honest: the girl looks fantastic, and you have to hand it to her for participating in a segment like this. Thankfully, Fallon stays mostly positive — except when it comes to his own undergarments. I'll let you watch for yourself.