Allison Williams 'Girls' Sex Act Stuns Newscaster Dad 1Allison Williams, daughter of NBC “Nightly News” anchor Brian Williams, will perform a sex act in her first appearance on the new HBO sitcom “Girls,” and the straight-laced newsman is none too happy about it.

Allison, who graduated from Yale in 2010, has been pursuing an acting and singing career. She vaulted into her role on the HBO series after “Girls” producer Judd Apatow spotted her in a YouTube video.

In the video, she performed a mashup of “Nature Boy” set to RJD2’s “A Beautiful Mine”, the theme song for the television series Mad Men. She’s backed by a full orchestra. The clip has received about a half-million views.

She was cast shortly after and credited her experience at the Yale improv group “Just Add Water” for passing the audition. The show is sort of the anti-Sex And the City. A small group of twenty-something friends try to make it in New York City, and must suffer through the slings and arrows of life in the big city.

Dad Brian Williams is reportedly embarrassed because his 23-year-old daughter will perform a masturbation scene on the first episode on Apr. 15, according to The National Enquirer.

Dad reportedly closed his eyes when his daughter’s sex scene came on during an advance screening of the first episode.

“Poor Brian got the shock of his life watching the scene,” revealed a friend. “Allison was beaming with pride that she has a starring role on a TV show, but all Brian saw was his little girl getting down and dirty.

“Allison noticed her dad squirming and told him, ‘You know it’s only acting! That’s a character, not me on the screen.’ But Brian told her, ‘It sure looks like you – don’t you care what people are going to think of you?’”

“Brian envisioned her working on some English period piece, not pleasuring herself on-screen! It makes him cringe that old friends are now coming up to him and saying, ‘Your daughter – wow!’” the source said.

Check out an clip of the scene.