Apparently geese are really mean. There's even a whole eHow.com article about how to stop a goose attack. It says the key is to "project confidence while retreating", so keep that in mind.
In any case, geese are mean, and American Funniest Home Videos has a video that basically proves as much. Not only does the goose attack the poor, innocent golfer who's probably just looking for his ball by the lake, but it goes after him again while he's running away. Working theory is that the goose detected his lack of confidence.
Here's a GIF: