In Chapter Three what group do Amir and Baba see while they are fishing

Baba and Amir saw "hippies" while they were picnicing by the lake.

On Fridays, the lake was bustling with families out for a day in the sun. But it was midweek and there was only Baba and me, us and a couple of longhaired, bearded tourists-­‐-­‐"hippies," I'd heard them called.