File this under: Gross!
Khloe and Rob Kardashian shared some serious brotherly/sisterly love online today ... and it definitely crossed the line from funny to inappropriate.
Rob kicked off the mutual admiration by declaring his sister his Woman Crush Wednesday of the week and sharing a photo of her on Twitter. Seems innocent enough at first, until you see the photo he attached to the tweet -- a pic showing Khloe putting her booty on display in a pair of sheer leggings (above).
Khloe quickly responded, posting a screengrab of her bro's message with the caption "Totally a normal brother/sister relationship. Incest is best!!! #HeyBooHey."
Fans quickly started commenting on both Twitter and Instagram, pointing out how bizarre it was to see siblings talk like that to each other.
Clearly it's a joke ... but a sick one!
This isn't the first time Khloe has referenced having an unhealthy relationship with her brother. When she hosted "Chelsea Lately" back in April, she also brought him up in a sexual manner.
"Rob's been on my mind a lot lately because we're currently living together," she continued. "And no we're not sexually involved, my bother's nearly not black enough for me!"
Safe to say nobody thought they were "sexually involved" ... until she brought it up!