The Eggcorn Database
eggcorns.lascribe.net
eggcorns.lascribe.net
They are the intersection of an idiom or colloquialism and a mixed metaphor. Examples include “I'm running a little behind the eight ball” or “really went the extra mile in his shoes.”
The language stack exchange, maybe? Social networks #linguistics tags?
Mixaprop can stand in as a name until we find one more true
Scrambled eggcorns
Poor man toes
I still like yours better
Here's the relevant part: "sometimes people also like to play with mixed metaphors. It can be a fun way to turn a cliché on its head. For example, I’ve seen people mix the metaphors “Let’s cross that bridge when we come to it,” meaning let’s put off the decision, and “Don’t burn your bridges” meaning don’t destroy a something you’ll need later. They get “We’ll burn that bridge when we come to it,” which combines the meaning of the two metaphors into something like “We’re ready to fight when the right time comes,” and still maintains imagery that makes sense."
"We’ll burn that bridge when we come to it" seems to be considered a mixed metaphor, rather than anything more exotic.
Common ones I hear are "I'll cross that bridge when I come to it" - to delay an action or decision and "Don't burn (all) your bridges..." - leave a path open for a reversal.
That’s the usual interpretation I’ve seen, yes. It’s a mix between the other two metaphors you mention, with the humorous implication that the speaker is going to delay taking an action until dealing with it will cause further problems.
Example sentence: “My manager doesn’t know I can’t work on Wednesday, but he hasn’t posted the schedule for the week yet so I’ll burn that bridge when I get to it.”
But on the other hand it's possible that in 2124 everybody considers "bi-election" normal as duh, there was an extra election, that's two, so bi-election, losing the analysis which got us the current word "by-election".
There are eggcorns related to the manor/ manner distinction, in particular "bedside manor" seems like a pretty obvious misanalysis. But you're correct that both "to the manner born" and "to the manor born" are considered reasonable idiomatic English.
Worst case Ontario right there.