In February 2020, Matthew Perry, then 50 years old, finally decided to join Instagram. If that wasn't enough to break the internet, fans were giddy to learn the now-deceased actor was affectionately known as "Matty" on the set of Friends. 

After Lisa Kudrow broke the news, Jennifer Aniston commented on the post with "Yay Matty! Could you TAKE any longer?" Courtney Cox followed with, "Yes Matty!!!"

And, of course, his Instagram handle? mattyperry4.

Apparently, Jennifer Lawrence herself has a unique nickname, though it's limited to her two older brothers. In an interview with 60 Minutes, the Hunger Games actress revealed that they still call her "Nitro," short for "nitroglycerin," because of how "hyper" she was as a child.

Many people know that pop star Lady Gaga was born Stefani Joanne Angelina Germanotta, but very few actually call her that… except for her A Star Is Born costar, Bradley Cooper.

At the American Cinematheque Gala in 2018, Lady Gaga teared up as she honored Cooper. 

"When we do these Q&As and things together, sometimes you call me Gaga, but we both know that you call me Stefani," she said. "I ran from Stefani for a long time, and I put on a superhero cape and called myself Lady Gaga.”

“He challenged me to deep dive into a place where I had to see her again. Where I had to be Stefani again."

The Ocean's Eleven superstar's full name is actually "William Bradley Pitt." Whether he goes by Brad for showbiz is unclear, but a woman revealed to PageSix that in a flirtatious encounter at an LA coffee shop, the actor known for his looks called himself "William," to which she replied, "Oh, you look like a Bradley." 

"Well, that's my middle name," Pitt said with a wink and a smile.

Blake Shelton is proof that no matter how famous you get, you'll always be your mommy's little boy. In an interview with Men's Journal, the country singer's mother confided that she nicknamed him "Toad" as a kid because he always brought small animals into the house, a nickname she still uses.

His classmates called Prince George, Prince William, and Kate Middleton’s now-10-year-old son "P.G." while he was attending Thomas's School in Battersea.  

While on The Tonight Show, the Oscar-nominated actress told Jimmy Fallon that she's only known as "Anne" because she thought she had to write her legal name when getting her Screen Actors Guild membership. In reality, she hates the name and goes by Annie with those who know her.

"The only person who ever calls me Anne is my mother," she said. "And she only does it when she's really mad at me."

In his memoir, Prince Harry revealed that Prince William actually calls him "Harold" when they're together. That might not seem so strange, except that Harry isn't short for Harold. The prince's real name is Henry. 

In a viral Instagram post, Bella Thorne filmed herself embracing her Blended costar Drew Barrymore. "I love my Pickle," Barrymore cried, apparently using a pet name for her fellow actress.

That one makes a little more sense, though.

Born in Barbados as Robyn Rihanna Fenty, the Grammy-Award-winning singer is still known by her first name to those close to her.
Speaking with Glamour, she confided, "When people call me Robyn, my head just flies around because I feel like that person knows me. But Rihanna, that tends to be people's own [creation]. Robyn is who I am. Rihanna—that's an idea of who I am."

Christopher is the model-turned-actor's real first name, but since there was already a Chris with his modeling agency when he signed up, he started using his middle name, Ashton. However, he's always gone by Chris in his personal life, including with his wife and That 70s Show costar Mila Kunis.

However, on an episode of Armchair Expert, Kunis revealed using the actor's first name took some getting used to. When they first started dating, she called him "Kutch."

The Superbad actress was born "Emily Jean Stone." Apparently, some in Hollywood still call her that because Olivia Colman even referred to her as Emily in her Best Actress Oscar acceptance speech.

In an interview with ABC News, the French-American actor told Peter Travers that people call him a lot of different things. Of course, many call the 28-year-old "Timmy," but, apparently, he also went by "Little Timmy Tim" when he was a rapper. Chinese fans often call him "Sweet Tea" as well due to the translation of the Mandarin adaptation of his name.

For us, it's impossible to see the star, who's been on screen since the 50s, as anything other than a Christopher, but as he revealed to Salon, that's not actually his name. He was born Ronald Walken and only became Christopher after singer Monique Van Vooren started calling him by the stage name.

Though he's Christopher or even Chris to most people now, his friends from the old days still call him Ronnie. 

Apparently, she earned the pet name due to her "short attention span." We're guessing Ashton Kutcher doesn't use this one.

In fact, the Wolverine actor known for his incredibly chiseled physique apparently earned the name because his legs were so skinny. Something tells us this nickname's been retired…

Meghan Markle's makeup artist and close personal friend, Daniel Martin, told People that he was nervous to see the Suits actress after her marriage to Prince Harry. "I asked her that. 'Do I bow to you? I don’t want to disrespect you, but I’ve known you for almost ten years. What’s up?'" 

Apparently, the Duchess of Sussex started laughing and eased his fears. "I'm always going to be Meg," she said.

But, hey, we think "Princess Meg" has a quaint ring to it.

Calvin Harris is only the DJ's stage name. He was born Adam Richard Wiles. However, speaking to Shortlist, he revealed he doesn't actually like being called "Calvin" by people and insists those close to him use his real name.
 
"No one calls me Calvin. It’s horrible, and it’s not my name. You might as well be calling me Mr Blobby," he said. "My name is Adam."