I slept like a dog last night

Dogs sleep pretty soundly, but this is definitely a malaphor.  It is a mash up of “slept like a log (or baby)” (restful sleep)  and “let sleeping dogs lie” (do not instigate trouble).  Nice mix up as it involves assonance (log, dog, and lie, like) and similar words in the phrases (sleep, dog).  This beauty was uttered by John Costello, one of my roving malaphor reporters!