What are some metaphors in The Great Gatsby?
Because Fitzgerald's great novel fits together so well, many of the metaphors will have symbolic importance. For example, when Nick thinks "Conduct may be founded on the hard rock or the wet marshes…" he's using a metaphor. Human conduct isn't really founded (built) on anything. (That's page 6 in my version of the book.) However, it's also symbolic of Gatsby, since he got his break when he was working on the water, and so his character isn't founded on anything. Likewise, when he describes East and West Egg as eggs, and the water as "the great wet barnyard of Long Island Sound," it is a metaphor for how things (fortunes, reputations, etc.) grow there—but it is also symbolic. That's even true of the line of the same page saying a house has a "thin beard of ivy." That's a metaphor for thin plant growth—but it is also symbolic of Gatsby's shallow persona.
I continue to be surprised and confused at the number of food metaphors in The Great Gatsby. At one point a ceiling is described as having the texture of the frosting of a cake. And there are a number of further comparisons to cake throughout the novel as well as other foods.
The throwing of the shirts is a metaphor for attempts to attract Daisy. Gatbsy's colorful shirts always remind me of a peacock using his bright colors to attract a mate. He gets frustrated and throws them around the room.