Kaley Cuoco is serving up a dose of nostalgia in honor of her baby sister's birthday.
On Instagram, the Big Bang Theory alum wished Briana Cuoco a very happy 33rd birthday with a rare childhood snap and a sweet tribute. In the caption, she wrote, "Happy happy birthday to the best sister on planet earth! @bricuoco you are truly a magical human with so much to give. Everyone who knows you, adores you..NOONE makes me laugh harder! You have been there for me through every high and every low and I promise i will do the same for you..I love you to the moon and back again! This is your year!"