Hallucination Strip (1975) Lucio Marcaccini

Massimo and his youthful friends (supposedly high school students) are involved in drugs (and revolutionary politics). One of his friends is spoiled pampered rich kid named Rudy. In one perverse scene, he is bathed by his mother and a maid. Rudy is planning a "happening" and needs drugs for his party so he gives money to Massimo to buy them. But, Massimo uses the cash to hide away a pair of his co-revolutionary comrades. So, his only collateral is the antique box he stole and he fences it to a drug dealer, code-named "The Sicilian" At the "Happening" drugs (including acid) are freely taken and Rudy has a long trip which gives the film it's American title.