Can you believe Kourtney Kardashian is turning 40? Neither can we! In honor of the Keeping Up With the Kardashians star's big day on April 18, we've put together 40 of the eldest Kardashian's sexiest pics -- all from the past year! Kim Kardashian may have once said that her big sis was "the least interesting to look at" of the KarJenner sisters, but we think these sultry Instagram snaps beg to differ. Happy birthday, Kourt!