Mixed metaphors aren't easy to explain, but, hey, I'll take a stab in the dark at them.
"All the world's a stage" wrote Shakespeare. But...er...no, actually it's not. Very little of the world is a stage. Two thirds of the world is covered in water, for a start.
Of course what Shakespeare meant is that we, like actors, tend not to have too much control over what we're doing. (He probably meant all sorts of other stuff, too, but that'll do for now.)
Anyway, all the world's a stage is a metaphor. That's saying a thing is something it plainly isn't, in order to highlight something interesting about it.
The trouble is, once you've started using a metaphor you have to stick with it, because if you try to change horses mid-stream you're likely to find yourself high and dry up the creek without a paddle.
And then everyone will know you're not the brightest tool in the box.
A memorable example of the thoroughly mixed metaphor came from Boyle Roche, in the Irish Parliament:
'Mr Speaker, I smell a rat,' he said. 'I see him floating in the air. But mark me, sir, I will nip him in the bud.'
Oh dear. The trouble is that Mr Roche so surprises us with the rat in the first place that the poor creature stays firmly in our minds even when Mr Roche has forgotten all about him.
This is from a BBC Radio Sheffield phone-in:
'Steve Cotterill had already turned down one job, as he knew there was a bigger fish just round the corner.'
We can only hope Mr Cotterill took to his new job like a fish out of water, because you can't blame him for wanting to butter his own nest, can you.
There are loads of examples of mixed metaphors, and of course I don't want to go on until the cows turn blue in the face, especially as I'm sure we're all keen to see the light at the end of the rainbow.
Let's all enjoy our metaphors: but let's not try too hard, because it seems to be when people start burning the midnight oil at both ends that things go just horribly horribly wrong.
Thing To Use Today: a metaphor. Metapherien is a Greek word which means to transfer.