It is a term people use when someone is being silly. It is normally said with affection to the person being silly. I have absolutely no idea why the saying mentions a goose. maybe because people see geese as being silly. Who knows?
Octavious: "I had seen an octopus fly a kite one day."
Kevin: "Octopus don't fly kites, you silly goose!"
Kevin: "Octopus don't fly kites, you silly goose!"
by OpheliaRedRose May 8, 2013
 Get the Silly goosemug.
Get the Silly goosemug. Is the accumulation of vaginal fluid and Anal discharge after a sweaty day this is considered an aroma as opposed to an odor.
by Don Menna March 6, 2017
 Get the Goose Buttermug.
Get the Goose Buttermug. A nickname for your penis.
by Nick D February 24, 2004
 Get the wild goosemug.
Get the wild goosemug. by Gagglegurl July 10, 2015
 Get the Goose mouthmug.
Get the Goose mouthmug. by neil sheldon August 25, 2006
 Get the goosemug.
Get the goosemug. Someone who blindly follows a political or religious movement for the sake of nationalism or imposing their views onto others. The term refers the way Nazis used to march in line with each other. A Goose Stepper is similar to a "kool-aid" drinker.
Many devout supporters of the Republican or Democratic parties are nothing more than goose steppers.
by Carl Stawicki January 16, 2009
 Get the Goose Steppermug.
Get the Goose Steppermug. 