The budding model posted the pic without any caption, but the picture pretty much speaks for itself.
This isn't the first adult activity the reality starlet, who is still a few weeks shy of her 18th birthday, has engaged in over the past few days.
Earlier this week, Kendall and 16-year-old sister Kylie Jenner were spotted leaving a 21-and-over club, where it is rumored that they used fake IDs to obtain entrance, although a family source denies any wrongdoing.
Either way, the 17-year-old isn't holding much back in this photo, which will undoubtedly put the wrong idea in more than a few men's minds.
Do you think it was inappropriate for Kendall to post this pic?
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Gallery | Kendall and Kylie Jenner: Stylish Sisters