As if there weren't enough things to worry about going on in the world right now, actor Macaulay Culkin decided to make us all feel ancient with a tweet.

The famous "Home Alone" actor who portrayed little Kevin McCallister — ahem, a child in our hearts and minds forever — took to Twitter to be a real Debbie Downer.

"Hey guys, wanna feel old?" he wrote. "I'm 40. You're welcome."

Culkin was 10 years old when the first "Home Alone" movie came out in 1990... He turned 40 on Wednesday.

Culkin sent out another sorry-not-sorry tweet later.

"It's my gift to the world: I make people feel old," he quipped. "I'm no longer a kid, that's my job."

"Thanks a lot, f---er," Kathy Griffin replied.

"Nursing home alone," YouTube star DashieXP tweeted.

"Can’t wait to watch the wheelchair chase scene with Kevin, Marv and Harry," another user, @ADAMATION, quipped.

Culkin added he's planning on learning a new hobby as he enters this next decade.

"Since I'm 40 I think it's about time to start my midlife crisis," he posted. "I'm thinking of picking up surfing. Do you all have any suggestions?"

Below are several other celebs that are 40 years old!

Channing Tatum

Despite getting his start playing high school students in "Step Up" and "She's the Man," Tatum is now a casual 40 years old. He also has a 7-year-old daughter, Everly, with his ex-wife Jenna Dewan.

John Krasinski

It seems like just yesterday that Krasinski was playing a scrappy Jim Halpert and working at Dunder Mifflin, but that was actually 2005 to 2013. Now he's a father of two and starring in Amazon's "Jack Ryan."

Wilmer Valderrama

Valderrama is best known for playing teenage exchange student Fez on "That 70's Show" from 1998-2006. He's still acting and is on "NCIS" as Special Agent Nicholas Torres. He also got engaged this year!

Adam Brody

You might remember Brody from his role as Seth Cohen in the mid-2000s TV series, "The O.C." He too is 40 now.

Zooey Deschanel

It's hard to believe that "New Girl" star Zooey Deschanel is 40.

Olivia Munn

Olivia Munn used to be a correspondent on "The Daily Show" when she was 30 and starred as Sloan Sabbith in Aaron Sorkin's "The Newsroom." We're pretty sure she hasn't aged in the last decade!

Rebel Wilson

Rebel Wilson played a college student in "Pitch Perfect" in 2012 but she turned 40 on March 2 this year.

Ellie Kemper

Ellie Kemper is also an alum of "The Office," portraying doe-eyed receptionist Erin Hannon from 2009-2013. Most recently, she has starred in "Unbreakable Kimmy Schmidt" as the titular character.

Kristen Bell

"Veronica Mars" herself! Since getting her start in 2004 as a private investigator/high school student in the show, Kristen Bell has been super busy over the past 15 years or so — from playing the lead in "The Good Place" to voicing Princess Ana in "Frozen" to having two kids with husband Dax Shepard.