It was the home ground of Arsenal Football Club between 6 September 1913 and 7 May 2006. It was mainly known as "Highbury" due to its location and was given the affectionate nickname of the "Home of Football" by the club.
A highboy is when you take a dump in a urinal, but a PHILADELPHIA Highboy is when you take a runny dump in a urinal after eating cheesesteaks and beer.
12 step recovery jargon referring to someone new who talks about how great life is, now that they'resober. Usually meaning that the person is out of touch with reality.
The new guy seems pretty happy for a dude who has no job, no money and no family. He must be on a pink cloud.