Wherein a group of people go for a walk, out of the eyes of police and authority figures, to smoke up behind the railroad tracks. Did not originate in Philadelphia, but in DeKalb, IL. It was -started- by a man named Phil, infamous for sneaking up behind you and tapping you on the shoulder while smirking and saying, "Wanna go for a walk?"
"Man, we just got back from that Philly walk, and I'm fucking baked."
"Wanna go for a Philly walk?"