Busy Philipps’ Instagram is a gold mine of truths. She’s not afraid to open up about serious moments (like the time she acted like a true hero by saving her daughter from a scary pool mishap, and the time she shared a sweaty selfie in the name of bettering herself), but she also peppers in lighthearted bestie moments with Michelle Williams (like their makeup-free pic and shared beauty secrets). On Monday, the actress took to social media to share another bit of information: how Matthew McConaughey inspired a lasting inside joke between her and her famous BFF.

Michelle Williams and Busy Philipps

The revelation came when McConaughey appeared on Live With Kelly and Ryan while Philipps was filling in for cohost Kelly Ripa. The actor was there to promote his latest movie, The Dark Tower, and although there was clear bonding happening on air regarding their parenting styles, it was Philipps’ Instagram post after the interview that really made their conversation worthwhile.

“Wait. I didn’t get to tell this story cause when you’re hosting, you know, ITS NOT ALL ABOUT YOU,” the Cougar Town alum opened the Instagram caption alongside a photo of herself, McConaughey, and Ryan Seacrest. She went on to detail the first time she and McConaughey met at a pre-Oscars party in 2006, when Michelle Williams and the late Heath Ledger were nominated for Brokeback Mountain. “Matthew McConaughey came up to congratulate them and we were introduced,” she recalled.

“He talked with us for about 10 mins and when he left he said, ‘Heath, Michelle, congratulations and best of luck to you this weekend. Marc [Silverstein, Philipps’ husband], it was nice to meet you. WHIMSY, it was a pleasure!'” she emphasized of the name mixup.

Philipps “obviously” let the mistake slide, noting, “Who cares?!- he’s Matthew McConaughey! He can call me whatever he wants!” Plus, the experience gave the best friends a great new inside joke: “Michelle to this DAY sometimes calls me Whimsy. And it always makes us laugh,” she wrote.

And in case there were any doubts about this, Philipps ended the post with a confirmation that we didn’t need, but are happy to have: “Also. He’s so hot.”

Where did your favorite inside jokes come from? Tell us @BritandCo!

(h/t E! Online; photo via Frazer Harrison/Getty Images)