Ryan Phillippe's sister Lindsay shared this ridiculously adorable photo of the two of them from way back in the day, dressed as Pebbles and Bam Bam from "The Flintstones." "2 of the best halloween costumes. Thanks mom," Lindsay posted with the pic, which Ryan re-tweeted.
They weren't the only ones reminiscing about costumes from years past though.
Gigi Hadid shared a couple aww-worthy pics with her mom Yolanda Foster, Martha Stewart posted one from her childhood and stars like the Kardashians, Drake, Jimmy Kimmel, Jessica Alba and Channing Tatum have all shard amazing throwback shots of them trick-or-treating.
It's clear a lot of these stars were cute long before becoming some of the hottest celebs out there today!
We're living for some of these retro costumes -- which is your favorite? Sound off below!