I'm pretty sure thc is out of your blood in a couple of days or less anyway..I'll check.

Edit: Only a few hours according to this site.
http://www.marijuanapassion.com/How-...ur-System.html

So like..just don't smoke the day before? Assuming you're having to donate blood to buy it anyway, I'm figuring you wouldn't have any before a test.

second edit: You are a bitch.