Julia Roberts and Ellen DeGeneres. Picture: Screengrab/YouTube

Julia Roberts donned huge fake boobs and posed with a pie in a bid to get more Instagram followers.

The 'Pretty Woman' actress joined the social media site in June, and talk show host Ellen DeGeneres decided to use her own popularity on the photo-sharing platform to share some tips for the actress to establish a wider audience for her account.

Speaking on her talk show, Ellen told her guest: You famously joined Instagram, you have three million followers, I have 60 million, and so I'm gonna help you. I'm gonna show you how to get more followers, because I know how to get followers?"

Julia quipped: "Do I have to post a nude?"

Ellen replied: "Ultimately, yes."

A beach backdrop then appeared on the screen behind the pair, with the 60-year-old presenter instructing the actress to "act like you're on vacation" while a cameraman took photos.

She then said: "Now, the Kardashians are very popular. Bring out the... You are gonna thank me for this."

Dumbstruck, Julia was then given a pair of barely-covered fake boobs and a flowing dress to wear over the top.

Ellen said: "Do you want followers or not?"

Her guest replied: "I guess I'm supposed to but right now I'm not sure."

But Ellen said: "So you have that, that's gonna help. Food is very big, do you post food, food is big?"

Julia quipped: "It can't be bigger than this."

The 51-year-old actress was then left "so embarrassed" when culinary legend Martha Stewart walked on to the set, holding a pie.

The lifestyle guru told the 'Notting Hill' star: Cover the droopiness, hold the pie over your boobs."

As she posed for more pictures, Julia mused: "I have the strangest feeling I'm losing followers as I stand here."

After producing a childhood photo of herself for Ellen's "Throwback Thursday" suggestion, Julia was then given an even better selfie opportunity.

The host said: "How about if I bring out a friend from 'My Best Friend's Wedding', what if we bring out Dermot Mulroney and share this picture."

The actor then walked on set and embraced his friend and said: "I'm so happy to see you."

Julia exclaimed: "Oh my god. Dermot Mulroney is here!"