Internet users were treated to a rare sight this week.
No, not Kim Kardashian's large breasts. We see those all the time.
But Kim Kardashian's bared teeth and gums? Those scarcely make an appearance - and now we know why.
"See I do smile... even laugh on occasion," Kim wrote as a caption to the above image, which features her and friend Shamari Maurice at a Christmas party.
Kardashian then went on to explain why she so rarely looks happy in pictures: "Because it causes wrinkles," she wrote of smiling.
It's unclear whether or not Kim was kidding, but the reality star isn't exactly known for her sense of humor. She is known, however, for caring about her appearance above all else.
Late last week, meanwhile, Kim gave fans a look at a very unhappy baby, as North West met Santa Claus and reacted with tears.
But that bodes well for her smooth face, according to her mother's logic.
Kim Kardashian is THG's Celebrity of the Year #4 due to her marriage in May; her nude photo spread in Paper Magazine; her high-grossing video game; and her ability to remain relevant by just posting picture online.
We hate to admit it, but that's an impressive talent.