It’s not your average trip to the doctor. Patients at a brand new Northwell Health medical facility are being given the greenlight to get frat house high on magic mushrooms, MDMA and cannabis, while watching sports and chowing down on chips — all in the name of medical research. “We’re studying full doses that produce anywhere from a four to a six-hour trip ,” Nehal Vadhan, director of the Manhasset-based Feinstein Family human neuropsychopharmacology lab, told The Post in an effort to treat