Toxic and mental singer Britney Spears will play a secretary in her upcoming cameo in the sitcom "How I Met Your Mother." The show's star Neil Patrick Harris has revealed all about Spears' upcoming acting foray, dubbing her part a "very interesting role." He says, "I was shocked that Madame Spears was willing to come and do some acting! She hasn't acted in a while. She plays the secretary to another girl that Ted (played by Josh Radnor) is after."It will be very unlike any Britney we have seen before, and we have seen a lot of Britney recently." And Harris is intrigued about the prospect of meeting the troubled superstar: "What if she shows up on set and she is absolutely, totally normal and that whole thing has been a big ruse? She is smoking a cigarette and (says), 'Oh yes, it is all a big bit. I have a master plan.'