Doogie's Spears Cameo Shock

Neil Patrick Harris - aka 80s TV doctor Doogie Howser MD - is getting his head around Britney Spears’ cameo on his US sitcom How I Met Your Mother.

The singer will pop up playing a PA to the girlfriend of one of the key characters.

Neil told US TV show Entertainment Tonight: “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.”

The 34-year-old added: “She plays the secretary to another girl that Ted [Josh Radnor] is after. So, it will be very unlike any Britney we have seen before, and we have seen a lot of Britney recently.”

The episode will air on US TV on March 24.