ET spoke with “How I Met Your Mother” star Neil Patrick Harris about pop star Britney Spears and her upcoming appearance on the show, “I was shocked that Madame Spears was willing to come and do some acting! She hasn’t acted in a while. This is a very interesting role. It is very not like her at all in real life in any of her previous chapters. She plays the secretary to another girl that Ted (actor Josh Radnor) is after. It will be very unlike any Britney we have seen before, and we have seen a lot of Britney recently.”

Harris also says that the cast and crew of “Mother” are not gearing up for an onslaught by the paparazzi, because they film on a studio lot and not on location. He does kid around, however, floating a theory that the pop princess may secretly be a tabloid headline mastermind, “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.’”

WENN, ET