(NOTE FROM JAMIE: I was going to do riot juice in honor of "It's Always Sunny In Philadelphia." But that's straight grain alcohol and blue drank. It is highly dangerous stuff and not recommended for casual sipping during basketball games.)
In a previous episode of Mixology 2012, we learned that Washington D.C. has an official city cocktail: the Rickey.
Noting that their city lacked a definitive cocktail, Philadelphia Magazine staged a contest to create one. The main requirement was that the drink be "something that just screams Philly with the force of a thousand cheesesteaks." Also, that the defining drink of Philadelphia not be an appletini. Which you'd think would go without saying, but apparently the organizers felt there was some risk of the appletini winning.
The submissions were narrowed to six worthy finalists, which were sampled at a public event. (The link includes all six recipes, so you could evaluate the Philly-ness of them all yourself, if you like.)
The winning entry was submitted by a Mr. Rick Fitzgerald, who describes the concoction as "a bittersweet cocktail in honor of everything that is bitter and sweet about this tremendous town." He based it on an old-timey cocktail called the Aviation, which he chose "in honor of Philly's high-flying sports teams." We'll assume he includes Villanova in that group; certainly the Wildcats' existence has been both high-flying and bittersweet at times.
The recipe (from the "finalists" link above):
2 oz Bluecoat gin (made in Philadephia; available at Sweetbay)
1/3 oz Luxardo Maraschino Liqueur
1/2 oz fresh lemon juice
1/4 oz creme de cassis
Combine in a shaker, shake well and strain into a cocktail glass. No garnish, please.