On first viewing, it looked like a Tik-Tok riff on The Purge: a caravan of cars rolls down La Cienega Boulevard in Los Angeles. The passengers -- young men in keffiyehs, some draped to mask their faces -- stand and shout through sunroofs and windows. The cars honk incessantly. In the back of a slow-moving Jeep, one man waves a billboard-sized Palestinian flag while another shouts through a megaphone: "Israel kills women and children every day!"