Jennifer Anniston shook the world when she finally joined Instagram. She made it even more memorable by making her first post a photo of the "Friends" cast having dinner!

With her current 16 million followers, only one stood out though.

The "Murder Mystery" actress' ex-husband, Justin Theroux, was one of the thousands of people who commented on the photo of Aniston together with her "Friends" co-stars Courteney Cox, Matthew Perry, David Schwimmer, Lisa Kudrow and Matt LeBlanc.

The "The Leftovers" actor seemed to be her number one fan after he commented "Woot-Woot! #first" on Anniston's first post to welcome the actress on Instagram.

On Theroux's recent interview with Extra, he spoke about his ex-wife on national TV nearly two years after their divorce. He also recalled that during the two years of their marriage, the actress pledged not to join Instagram.

Luckily for all of us, Anniston has it now -- even causing gltiches on the social networking site after the influx of her followers. Compared to millions of followers of the "Friends" star, Theroux currently has 729,000 fans (they were not in a competition and he was really happy about it).

"The world is about to learn what a hilarious woman she is if they don't already. She's gonna be good at this," he went on. He also added that he is proud of his ex-wife who made this "milestone".

The Anniston fever did not stop there.

Per Entertainment Tonight, Theroux, the voice actor of Tramp, revealed that during the press conference for the Disney's Lady and the Tramp live-action version in New York, Aniston texted him and argued about not following her. He immediately explained that he was "caught in the glitch," making him unable to hit the "follow" button.

Theroux also revealed to Access Hollywood the truth behind his "first comment" on Anniston's first Instagram throwback photo. He clarified that he was not the first person to follow her, and it was actually a joke since the whole internet knew that the actress' followers stormed to her account as soon as she made it.

Just like what her ex-husband told all the interviewers, Aniston became one, if not the most hilarious IG user on Earth.

Jen has now three posts on her Instagram page, with the third post showing a hilarious set of photos that broke the internet. She nailed the internet game with an  "I woke up like this" and "I'm just a girl" photoset. She posed while wearing a cozy white sweater-turned-into-dress with socks and sandals.

Aniston and Theroux  seem to remain friends despite being ex-lovers. Recently, they reunited to grieve about the death of their dog, Dolly. In addition, on Feb. 18 of this year (which was one year after their divorce), the actor celebrated Anniston's 50th birthday with an Instagram post, referring to her as a "fierce woman".

Tags: Jennifer Aniston Justin Theroux