Kim Kardashian Mistaken for Pregnant Sis Kourtney

Kim Kardashian Kourtney Kardashian pregnant

Some people just can't tell those Kardashian sisters apart.

Kim Kardashian wrote on Twitter Monday that she was congratulated for being pregnant. The only problem: big sis Kourtney is the one expecting.

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"Some woman just came up to me & said congrats 4 being pregnant! I know she thought I was Kourt but rude! Do I look 8 months preggo?" Kim moaned on Twitter.

The reality star, 29, had the encounter after visiting a doctor's office.

"I'm not feeling so good today. I have a cold & Kourtney made me go 2 the Dr. 2 check 4 Swine Flu!" she wrote. "I'm fine Dr. says, NO SWINE."