Is it ok to date your Uncle's wifes sister?

Here's the deal? My uncle (Moms brother) married a woman about 5 years ago.(My aunt through marriage). Her sister is 19 and I am 24. She has been flirting with me big time. She is kinda well..... naughty. She has been coming onto me a lot lately. My question is, would it be weird if I started dating her? Just to recap. She is the Sister of My blood uncles wife. This chic is driving me nuts and I just want an opinion if its cool to go ahead with it.