The fact that we even have to question this is pretty gross!

Kendall Jenner swung by to pick up a friend in her vintage 1957 Corvette Stingray today in LA, and the model was none too pleased when our videographer asked about Justin Bieber! Specifically, she didn't like when he asked whether The Biebs was having his way with her or her sister Kourtney!

Why would we ask such a question? Because the people want to know! Way back when they first became friends, rumors swirled that JB and Kenny had a fling, and now it's being reported that he has been secretly doing the bone dance with Kourt for the past four months!

Just last night, the supermodel partied with the "Sorry" crooner at The Nice Guy in West Hollywood, which coincidentally is the same place he was spotted with the eldest K sister over the weekend, so we gotta wonder...