Neil Patrick Harris

The 40-year-old actor is portraying the title character in a new Broadway production of musical 'Hedwig and the Angry Inch' which will hit the New York stage next year.

Although Harris is excited about the role, he has been told to lose his eyebrow hair to play the East German transsexual - who is left with no genitals after a sex change operation goes wrong - to achieve a realistic look.

He said: "In drag, you take a glue stick and if you don't shave your eyebrows, you have to glue stick the whole eyebrow, blow it dry and then do it again like six times for each eyebrow. You paint the other eyebrows, the feminine eyebrows, above it.

"They might never grow back; I'm terrified of that!"

Harris admits he is "freaking out" about playing the part because the production - which originally hit theatres in 1998 - is so challenging.

Speaking to chat show host Conan O'Brien, he said: "I'm playing the role of Hedwig but yes I'm playing a transgendered German rock singer. So I'm gonna have to be like all dragged out ... I'm freaking out, how do you prepare for that? It's very transformative, the drag thing is not supposed to be shocking, it's well beyond that."

The 'Smurfs 2' star will finish filming the ninths series of TV sitcom 'How I Met Your Mother' before starting rehearsals for the musical.