I enjoyed Fentanyl three weeks ago, before surgery. IV. It is dirt cheap as a drug - the anaesthetist told me that it is around 50c per dose, and one dose put me right out there on another planet. The second dose a few hours later made me feel amazing, worryingly so in fact. I would strongly advise taking it unsupervised or as a recreational drug though - it is VERY heavy stuff. And extremely addictive apparently. Leave it for the hospital.