Is there any fast way to get hash out of my system ?. i'll go under blood test within 12 days and i quit smoking since 3 days.

No proven way: I know of no way to clear marijuana/thc from your body more quickly. If you were not a heavy smoker you will likely pass most tests after not ingesting marijuana for about a week, but it depends on how sensitive the test is. Here is a wide-ranging discussion on this topic (not by docs) that is interesting: http://forum.Grasscity.Com/apprentice-tokers/1047449-how-beat-urine-drug-test.Html.