And she wasn't kidding. Every few hours, an even sexier snap showed up on the social media site...like this one...
...and this one.
...ANNNNNDDDDDDD this one.
TBH, we were kinda worried she was going to be naked by by the end of the day, but she actually kept herself more covered than sister Kendall Jenner did on her 18th birthday. When Kendall hit the milestone, she freed the nipple in a big way by sharing this photo of herself wearing totally see-through, sheer top.
Happy birthday, Kylie!