The Curse of the Billy Goat was supposedly placed on the Chicago Cubs baseball team in 1945 when Billy Goat Tavern owner Billy Sianis was asked to leave a World Series game against the Detroit Tigers at the Cubs' home ground of Wrigley Field because his pet goat's odor was bothering other fans. He was outraged and declared, "Them Cubs, they ain't gonna win no more," which has been interpreted to mean that there would never be another World Series game won at Wrigley Field. The Cubs have not won a National League pennant since this incident and as of 2013 have not won a World Series in 105 years.
Sam Sianis, nephew of Billy Sianis, has been brought out onto Wrigley Field with a goat multiple times in attempts to break the curse: on Opening Day in 1984 and 1989 (in both years, the Cubs went on to win their division), in 1994 to stop a home losing streak, and in 1998 for the wild card play-in game (which the Cubs won).
In 2003 (incidentally, the Chinese zodiac's Year of the Goat), a group of Cubs fans headed to Houston with a billy goat named "Virgil Homer" and attempted to gain entrance to Minute Maid Park, home of their division rivals the Astros. After they were denied entrance, they unfurled a scroll, read a verse and proclaimed they were "reversing the curse." The Cubs won the division that year and then came within five outs of playing in the World Series.
According to three interviews with Sam Sianis, William Sianis' nephew-in-law, the Curse of the Billy Goat can be dispelled only by the Chicago Cubs organization's showing a sincere fondness for goats; allowing them into Wrigley Field because they genuinely want to and not simply for publicity reasons. (According to an account in the Chicago Sun of October 7, 1945, the goat was turned away at the gate, and Sianis left the goat tied to a stake in a parking lot and went into the game alone. There was mention of a lawsuit that day, but no mention of a curse.)