St. Anthony is generally known as St. Anthony of Padua, for the city in Italy in which he died. But he spent his life as Fernando Martins, the son of a wealthy Portuguese family in Lisbon. He is now the city's favorite saint (although not its patron saint), and the eve of his feast day, June 13, is quite the to-do.
The legend is that St. Anthony was being heckled by a crowd while trying to preach so he stood on the edge of a river and preached to the fishes, who popped there little heads above water in order to hear him. He is often depicted in artwork with fish.
So, as block parties begin blasting music, clouds of briny smoke cover the city as thousands of sardines are grilled on street corners and impromptu courtyards-cum-bistros. The fresh fish, about 6 inches long, are heavily salted and thrown directly on the grill, then generally tucked into a puffy roll (more for ease of transport than as an integral part of the dish, as far as I could tell). They are tender and thin-skinned and have a notably fishy taste not found in their more common tinned brethren. While their strong taste and profusion of tiny, throat-scarring bones might be intimidating to a novice, Lisboans love them. Sardine hats, sardine stickers, sardine everything make an appearance among carts selling beer and bifana, a Portuguese pork sandwich that is frighteningly addictive.
St. Anthony is also associated with lost items and with matchmaking, leading to a number of traditions revolving around finding one's soul mate, including the marriage of a few couples in a mass ceremony celebrated throughout city. People also buy their sweethearts small basil plants with silly love poems tied to them.
Not sure if he's also the saint associated with drinking beer all night, but that happens, too.