'Easy A' star Emma Stone dropped by CBS' 'Late Show with David Letterman' this week, and talked about celebrating a deeply meaningful milestone with her mom -- by getting inked on each of their wrists.

"Two years ago....she got diagnosed with breast cancer," said Stone. "And she's out of the woods now, which is amazing."

The actress also told Letterman, "We've never gotten tattoos before, and probably never will again."

She's certainly unlikely to find a more famous tattoo designer: none other than Paul McCartney provided a custom sketch to Stone and her mother, based on one of the Beatles' classic hit singles.

"My mom's favorite song is 'Blackbird,' and it's my favorite song as well," she explained on the show. "I wrote a letter to Paul McCartney asking him if he would draw two little bird feet, because he wrote the song. And yesterday, he sent them to me."