Efron’s birthday serenade

Zac Efron

Zac Efron serenaded Ellen DeGeneres for her birthday.

The 26-year-old actor taped an appearance airing on the comedienne’s US talk show on Thursday, four days after she turned 56.

“Zac actually told me during the break that he doesn’t play guitar but he learned to play guitar and wrote a song for me on my birthday – and so I’m gonna hear a song!” she gushed to the audience as Zac pulled out an acoustic guitar.

The former High School Musical star explained he wasn’t sure what else to do for the chat show host, so he pulled out all the stops.

“I kinda thought, ‘What do you give somebody for their birthday who has everything?’” he said before jumping into a version of Stevie Wonder’s Happy Birthday.

“You didn’t write that song!” Ellen laughed.

Zac is currently promoting his new movie, That Awkward Moment.

The Hollywood stud opened up about the now infamous scene that sees him planking naked on a toilet.

“You know what was really weird though, is like before the movie or like anyone even know about the movie before we finished filming it that picture came out,” he said.

“So like that was like the first thing anybody knew about the movie and so like my parents were calling me going what the hell is this picture?”

That Awkward Moment tells the story of three men dealing with the confusion of whether or not to move forward with their romantic relationships.

The Tom Gormican-directed film opens in US theatres Friday.

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