Insurance for what? HIV? Most medical insurances won't cover you for a pre-existing condition if you haven't had insurance within the past six months. Depending upon the state you're in, there are a few different options available, but none are going to get you insurance "fairly quickly"--I know I had to wait more than a month for mine to kick in because of when I applied/was accepted.
We'd need a lot more information to help you out... Age, income, residency, past medical insurance, ... I doubt you're willing to divulge that type of information in such a public place. Your best bet is to look into
Medicaid or other state health care programs. New York, for instance, has "Healthy New York" for low income people/families.
If you're outside of the US, there's even less that we can do to help you out. Wishing you and your friend the best of luck.
OH, are you aware there are clinics that will test you for HIV for free? I got tested for free at a local LGBQ place.
