Kim Kardashian: "Mason Is Soooo Handsome!"

Credit: Flynet

Kim Kardashian can't get enough of her sis Kourtney's baby boy.

"Words just can't describe how I feel about Mason! I'm sooo in love w my nephew! I just woke him up for a kiss!" Kim, 29, Twittered of the 3-month-old Tuesday morning.

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A few minutes, later she added, "Mason looks just like Rob and my dad! He's soooo handsome." (Dad is famed O.J. Simpson defense lawyer Robert Kardashian, who died in 2003 of cancer.)

Kourtney, 30, Twittered about her son as well.

"Morning jog w @kimkardashian on the beach! no better way to start my day...well, a smile and a kiss from mason," she wrote.

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The sisters have been in Miami taping their E! reality show, Kourtney & Khloe Take Miami (on which Kim guest-stars).

On Friday, they took baby Mason shopping for a $136,000 Maserati, which Kim will drive in Miami.

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"It's a ridiculous car and I think it's the first one in the U.S. or something crazy like that!" wrote Kourtney, who added that Mason was rocking a "little cashmere outfit from Neiman Marcus brand and Trumpette socks" on the outing.