gee willakers!
Expression of surprise. Not sure of origin, but possibly evolved from the following conversation:
Fred: "I inherited several square feet of land?"
Will: "No, dad gave you several ACRES!"
Fred (surprised): "Gee, Will, acres?!"
Fred: "I inherited several square feet of land?"
Will: "No, dad gave you several ACRES!"
Fred (surprised): "Gee, Will, acres?!"
Gee willakers, this 'mummy' costume I'm wearing has no zipper!