Now this is an epic #tbt!

On Dec. 10, 2015, Blake Lively posted a #tbt of herself as a little girl hanging out with "Beverly Hills, 90210" star Jason Priestley.

She captioned the snap: "#tbt to when Serena Van Der Woodsen and Brandon Walsh were a thing. (Shh don't tell @robynlively 😊😉😝)"

Fun fact: Jason Priestley and Robyn Lively -- Blake's older sister -- dated briefly in the 90s.

Gotta love Blake Lively's sense of humor!