A malaphor is a humorous cross between a metaphor and a malapropism.
An example by Douglas Hofstadter in his Pulitzer Prize winning book Gödel, Escher, Bach: An Eternal Golden Braid involves an AI attempting to determine if two sets of patterns are similar. By his theory, this could be achieved by the AI stepping one after another through all of the concepts it is aware of, matching these concepts against each pattern, and thus identifying common elements between the patterns. He points out that the AI should successfully complete this process even if it begins by "barking up the wrong alley" for a while. He credits newspaper columnist Lawrence Harrison for coining the amusing term.
Source: "Gödel, Escher, Bach: An Eternal Golden Braid" pg. 657