According to Merriam-Webster, a mondegreen is:
a word or phrase that results from a mishearing of something said or sung [“very close veins” is a mondegreen for “varicose veins”]

A similar slip of the ear resulting in a mishap of the pen (or, more likely, keyboard) has been called “malcliché.” My teaching experience leads me to ascribe the uptick in these peculiar forms of malapropism to AutoCorrect and to a more aurally-based society. We have moved from ancient oral communication to text and back again to what we hear/see rather than what we read. As our media becomes a place where diversity abounds, the conventional structures of English–idioms and phrasings in particular–fall apart a bit as we speak with different speeds, different accents, and under different cultural, regional, rhetorical, and other authorities.

I have been collecting a few from student papers and from conversations I overhear. Yes, I eavesdrop–I’m a writer!

I supply a few here for your amusement and puzzlement, and as inspiration. A few of these phrases are potentially rich in imagery that’s strangely appropriate, such as “burning your britches,” “poor self of steam,” “rake him into the coals,” and “beg to defer.” I have successfully used mondegreens as poem prompts. I do not recommend using them in English comp papers, however, as they result in coffee spills produced by professorial giggles and rampant use of the red pen admonishing “sp” and “clarify!”

armed to the feet
above bored
stuck to me like a leash
all intensive purposes
board to death
buy the same token
queen of the crop
caught me on guard
don’t count your eggs before they hatch
a fool and his money are soon apart
give it a swirl
dead wait
leaving like flies
go out on a tree
grin and bare it
taking his name in vein
one fell sweep
in the nickel of time
hair-brained
last ditch effect
pearls before swans
unnecessary evil
no holds bard
on a role
past the buck
the past of least resistance
sharp as attack
he got just his desserts
what goes around must come down
on tender hooks
preaching to the chair
no ifs, ands, or butts
free rain