I Love the English Language
The blending of idioms or cliches is called a [i]malaphor[/i]. Examples:
"We'll burn that bridge when we get to it."
"It's not rocket surgery."
"You can take one man's trash to another man's treasure but you can't make it drink."
"Not the sharpest egg in the attic."
"You can't have your bed and eat it too."
"You opened this can of worms, now lie in it."
My favorite:
"...until the cows freeze over."
"We'll burn that bridge when we get to it."
"It's not rocket surgery."
"You can take one man's trash to another man's treasure but you can't make it drink."
"Not the sharpest egg in the attic."
"You can't have your bed and eat it too."
"You opened this can of worms, now lie in it."
My favorite:
"...until the cows freeze over."