malaphor
An idiom blend: an error in which two similar figures of speech are merged, producing an often nonsensical result.
rare
What I conclude from this admittedly narrow data base is that, while the malaphor flourishes in bureaucratic compost, it will grow just about anywhere. The following malaphors are my pick of the letters. They were uttered in the home, on the farm, in the street.
Where it comes from
Blend of malapropism + metaphor; attributed to Lawrence Harrison in the Washington Post article "Searching for Malaphors" (Aug. 6, 1976).
Adapted from the Wiktionary entry malaphor (CC BY-SA 4.0).