I liked Dick Nixon’s thoughts on political fundraising:
“It’s hard to build that big fire if you go to the well too often”
“sweating like a stuck pig” - I used to say that as a kid, I reasoned it as a pig being stuck up to his knees in the mud on a hot hot day and not being able to move at all…I sure didn’t think of “bleeding like a stuck pig”–ewwwwww (I hope I have that right! LOL)
My dad was heading up a fundraiser at my highschool when I was a senior. At a planning meeting when a number of parents were brainstorming and setting milestones to reach our dollar goal, Dad announced to all present that should we get close, the principal could help us out because he had “an ace up his hole”
Here is one from my sister. “Great minds always run in the same gutter.”
“You’re like a dog barking down the wrong well.”
Had a client say that in a meeting, damn near hurt myself trying not to laugh.
Same client said:
“You’re like a dog running around a track banging your elbows on the rail.”
Followed by an awkward silence as we all tried to figure out what the hell it means. I still don’t know, but I try to use it at least once a week…
grem
These were said by a friend of mine, maybe not exactly mixed metaphors but pretty damn funny:
“She’s skating on thin water.”
“My parents got married out of wedlock.”
When I heard the last one I came totally unhinged and fell out of a chair.
Even a leopard can’t change its spots in the middle of a stream.
Well, thats as clear as a bull in a china shop.
One of the all time best lyrics in rock. Not funny, but profoundly deep.
We now return you to your regularly scheduled thread
An uncle of mine, not on his best day, once cracked us up with these:
“He was all over her like butter on a shitwagon!”
(He claimed he meant to say “buzzards”, like that helps.)
“It broke buddy’s arm just like a potato!”
(Not really a mixed metaphor, just a really lousy simile.)
And another time, me and a friend were sitting in a movie theatre that lacked air conditioning.
Him: “Geez. I’m sweating like a bandit.”
(pause)
Me: “Right. We’ll just pretend that’s a saying and move on.”
Him: “Thank you.”
Maybe you had to be there.
That’s the best. Hands down. 
You win! Also…I liked “We’ll burn that bridge when we get to it.” That was good too.
Here’s another. That’s the pot calling the kettle of fish black.
One friend says: “you’re as sharp as a marble.”
Other friend replies: “oh yeah, you’re as dumb as a knife.”
“You’re as dumb as a knife” became an often used saying after that exchange!
You can put the cart before the horse, but you can’t make him drink.
“I don’t need a compass to tell which way the wind shines.”
– Mr. Furious, Mystery Men
my sister and i like to make up novle combinations of the classic insults of people’s inteligence:
a few tacos short of a six-pack
not the sharpest bulb in the drawer
smart as a box of hair
his elevator doesn’t go up to the bats in his bellfrey
a few beers short of a happy meal
you get the idea
People who live in glass houses may as well get up and answer the door! 
People who live in glass houses should get dressed in the basement.
Back in prehistoric times, when I was ten or twelve, I coined the phrases:
“Like ships from a sinking rat.”
And:
“One who feeds the hand that bites him.”
Still works for me to this very day. Ah, the joys of dyslexic being.
O joy!
Good to see this thread revived. I hadn’t laughed this hard in a month of coon’s ages. Let’s not throw the baby out with the watched pot. You don’t need a weatherman to know not to spit in the wind. Heads will roll uphill. Opinions are like assholes: everybody knows one. Call a spade a kettle. Hell hath no fury like a wet cat.
Peace,
TN*hippie
Note to self: swallow the coffee, then read these posts! Here are my dubious contributions: Don’t air your dirty linens by the seat of your pants. Fake it till the fat lady sings. Drunk as a church mouse. When hell freezes the balls off a brass monkey. Put a monkeywrench in your pipe and smoke it. Rules are made to be out of mind. It’s an ill wind that blows a blue streak. Too many cooks spoil the devil’s workshop. Like a fish with a fifth wheel. Better than a poke in the eye with the tail that wagged the dog. Wake up and smell the gift horse in the mouth. Face the music by my bootstraps. March to the beat of a dead horse. Close enough for rocket science. You catch more flies spinning your wheels. Ad infinitum…----Tabithina