The English language is an ongoing ad hoc stew with no recipe and no chef in charge. Every practitioner is free to toss in his own ingredient, be it of French, Italian, Greek, German, Arabic or Japanese in origin. Or simply make words up from scratch. Amazingly, despite its internal inconsistencies and lack of logic, this irrational stew turns out to be surprisingly useful for actual communication.
 
Why do we drive on a parkway and park in a driveway? You can't rationalize it. And you French speakers have no grounds to be smug, either. You've contributed your share to the stew as well, what with your randomly-placed accents and decorations. I live on a cul-de-sac. Literally "arse of the bag".

It's a bit like the American phrase "I could care less" which to me has the exact opposite of it's intended meaning. If you could care less then surely you care to some degree. In Britain we always said "I could not care less" which rightfully expresses your position as being at the very bottom of the caring scale. I can't help thinking that it was a case of Chinese whispers, a bit like the American spelling of "aluminum" as opposed to "aluminium."

Sooner or later, the ships will descend and we'll be informed that the experiment has failed and our ability to use language has been revoked. After that, things will make much more sense. 

Some of theorized that once everyone realizes what the world is about, it will immediately be replaced by something more confusing and inexplicable.  Others think this has already happened...

Another thing I see regularly is in using the word "worst" instead of "worse"....
 
I just don't think anything could be more worse than the worst bratwurst that's cursed.

"one in the same" instead of "one and the same"
"you've got another think coming" (HUH?) instead of "you've got another thing coming"
"could (should/would) of" instead of "could (should/would) have"
"could care less" instead of "couldn't care less" (a BIG personal pet peeve of mine!)
"what you be doing?" - "what have you been doing"
"ain't" ...I was taught to never use "ain't" because it was incorrect grammar.  Now it's in the dictionary!
how about "I hope to he!!"? what does that even mean?
"I learnt him" - WHAAAT????
"on accident" - you can't do something "ON" accident. - it's "BY accident" 
 
how about this one:  "statue of limitations" - really? - "statute of limitations"
"for all intensive purposes" - "for all intents and purposes" - come on, people! 
"extract revenge" - "exact revenge"
"I'm gonna ax you something" - "I'm going to ask you something"
"irregardless" - "regardless" - this one bugs my wife a lot, especially since my relatives in Tennessee say it a lot!
"unthaw" - "thaw" - another one my relatives use which bugs my wife!
"Scotch free" - "Scot free" - what...is the adhesive tape free?
"I've made a 360 degree change!" ...hmmm...well, I guess you're right back where you started?
 
and another big pet peeve of mine:  "mute" vs "moot" - this is even used incorrectly on TV's shows and professional announcements.  the words aren't even pronounced the same!!!  
 
how about "prostrate cancer" - what? is it lying face down?  
 
"sneak a peak" - uhm.  which peak?  Kilimanjaro? Fuji? Everest?
 
"honed in" - "homed in" - are we using a honing blade to "hone in" on someone's territory???
"baited breath" - "bated breath" - hmm...worms or crickets?
"by in large" - "by and large"
"peaked my interest" - again - which peak are we talking here?  McKinley maybe? the word is "piqued" 
"case and point" - which case are you pointing to? it's "case IN point"
 
I know there are many others.  they drive me nuts.

FSF instead of cul-de-sac?

bapu
FSF instead of cul-de-sac?

Best post by Bapu evah!! (in this thread).

The phrases, "I've heard it before," "Please, no," and "Mom, he's doing it again," are sometimes used to mean, "I'd love to hear more stories about the old days. Please, tell us another one and make sure to include references to people, places and events no one else knows or cares about."
 
Likewise, "Go away," "Get lost," and "Why are you still here?" often can be interpreted as "Please feel free to stay as long as you'd like. We don't need more than a couple of hours of sleep."
 
"What is wrong with you?" "Dude!" and "You are so gross," usually mean, "Watching you eat becan is like watching an exciting nature show during Shark week, only more visceral."

UbiquitousBubba
The phrases, "I've heard it before," "Please, no," and "Mom, he's doing it again," are sometimes used to mean, "I'd love to hear more stories about the old days. Please, tell us another one and make sure to include references to people, places and events no one else knows or cares about."
 
Likewise, "Go away," "Get lost," and "Why are you still here?" often can be interpreted as "Please feel free to stay as long as you'd like. We don't need more than a couple of hours of sleep."
 
"What is wrong with you?" "Dude!" and "You are so gross," usually mean, "Watching you eat becan is like watching an exciting nature show during Shark week, only more visceral."

Alex, I'll take common phrases in the FSF for $200