By Isabel Jones
Updated Nov 08, 2018 @ 12:15 pm

We’ve always known Princess Diana had a cheeky sense of humor (she gave Prince William a “boob cake” for his 13th birthday, after all), but it wasn’t until Julien’s Auctions unearthed a birthday card she sent to her accountant that we learned just how naughty the late Princess of Wales really was.

Diana Princess of Wales in Edmonton
Credit: David Levenson/Getty Images

Skirting professional niceties in a way we literally cannot imagine Kate Middleton or Meghan Markle doing today, Di sent her accountant, Tony (Anthony Burrage), a racy belated birthday card with a double entendre that was both insulting and referenced the importance of, uh, size

Princess Diana Card Embed
Credit: Julien's Auctions
Princess Diana embed
Credit: Julien's Auctions

Diana added a set of ellipses at the end of the punchline for emphasis, writing in her signature scrawl, “Tony, A belated Happy Birthday for the 5th! From, Diana.”

The card, which is part of the auction house’s “Icons & Idols: Hollywood” collection, will be available for purchase on Nov. 16-17, and is expected to fetch between $800 and $1200.