Anthony Michael Hall is opening up about his time filming “National Lampoon’s Vacation” with Chevy Chase more than 40 years ago.

During a cast reunion at Fan Expo Chicago on Aug. 17, the Rusty Griswold actor recalled how Chase, who played Hall’s on-screen father Clark Griswold, taunted him for hitting puberty between the end of filming and the reshoots six months later, per Entertainment Weekly.

“Puberty kicked in for me,” Hall, who was 14 at the time, began. “I was a foot taller and like a different kid.”

“Guess who pointed the s–t out right away and made me feel really good about it on set,” the “Reacher” star added while looking over at Chase.

But Hall’s behind-the-scenes story did not end there. He also brought up an autograph the “Saturday Night Live” alum signed for him when shooting on “Vacation” officially finished.

“I just remember the autograph you wrote me when we wrapped,” Hall, now 57, continued. “He goes, ‘To Anthony, you’re a regular Robby Benson.'”

“And then it was also, ‘If you’re going blind, you’re doing it right,'” Hall added.

Dana Barron, meanwhile, brought up how the 81-year-old comedian also made fun of Hall for having pimples.

Barron, 59, portrayed daughter Audrey Griswold in “Vacation.”

“By the way, you forgot the pimples,” she said during the cast reunion. “Remember, Chevy mentioned all the pimples on your face.”

However, Hall doesn’t harbor any ill will toward Chase for all the teasing, and clarified as much toward the end of the reunion panel.

“This is why I love being your son for 40 years,” he said to Chase. “I love you.”

After “National Lampoon’s Vacation,” which was released in 1983, Hall went on to star in several John Hughes classics, including “Sixteen Candles” in 1984 and “The Breakfast Club” in 1985.

“Vacation” follows the Griswold family as they take a summer road trip to a theme park and hijinks ensue.

Besides Chase, Hall and Barron, the cast was rounded out by Beverly D’Angelo, 73, who portrayed mom Ellen Griswold in the John Hughes-written, Harold Ramis-directed comedy.

Although both Chase and D’Angelo returned for the next two sequels, “National Lampoon’s European Vacation” in 1985 and “National Lampoon’s Christmas Vacation” in 1989, Hall and Barron were both replaced in each movie.

The reunion in Chicago also included the actors who played the kid Griswolds in “Christmas Vacation,” Johnny Galecki and Juliette Lewis. Chase took to social media to express how much he enjoyed the event and linking back up with his former co-stars.

“Great time this past weekend in Chicago … with old friends and new ones,” he wrote on Instagram alongside a video from backstage.

The “Caddyshack” star is scheduled to hit the road for an eight-show tour celebrating “Christmas Vacation” from Oct. 29 to Dec. 18.