From Elizabeth Daingerfield Zwicky, a link to a Malaphors site, featuring

Unintentional blended idioms and phrases – It’s the cream of the cake!

The site (managed by someone who identifies himself only as Davemalaphor) keeps a running inventory of “malaphors” — the term came to the site’s compiler from Douglas Hofstadter (1989), who got it from a 1976 newspaper article; Hofstadter also cites Gerald Cohen’s work on “syntactic blends” (generally, not specifically those involving idioms).

[Recent items on the Malaphor site: He’s a black horse in all of this (dark horse + black sheep); The client is one of those hard-moving targets (hard to hit + moving target); I’m going to give him a taste of my mind! (a piece of my mind + a taste of his own medicine).]

In a separate development, inspired by postings on “idiom blends” in Language Log…