STOCKTON — A young man was shot Saturday afternoon in northwest Stockton after getting into a car for what he thought would be a ride to buy marijuana, police reported.The 19-year-old victim was in a silver four-door Nissan Altima about 4:40 p.m. on Cosumnes Drive near Michael Faklis Park west of Trinity Parkway when the driver — who was known to the victim as “Ari” — pulled out a gun and shot him.