I'M A NATIVE BORN ENGLISH SPEAKER, BUT I STILL DON'T UNDERSTAND:

I can be efficient, deficient, sufficient, insufficient or even inefficient, but what happens if I'm only ficient?  If your ankle doesn't function as it should, why aren't you footicapped?  When you ask a barber to cut your, how does he know which one you mean?  If you used to be inept but you've finally figured out how to do things, are you now ept?  Why isn't phonetically spelled with an "f"? Aren't identical twins bique instead of unique?  I don't know, either!!

(A lot of the stuff below is from angelo.edu & a lot of it isn't.)

Lawyers get disbarred & clergymen defrocked, so why aren’t 
     ballplayers debased, 
     politicians devoted, 
     cowboys deranged, 
     models deposed (& Calvin Klein models debriefed), 
     organ donors delivered, 
     tree surgeons debarked, 
     musicians denoted, 
     electricians delighted--or coming unplugged, 
     carpenters deconstructed,

     guitarists in discord, 
     Supreme Court justices disappointed,
     songwriters decomposed or detonated,

     contortionists disjointed,

     pigs with laryngitis disgruntled,

     holes in your jeans dispatched,

     travel guides detoured,

     foals desired,

     students degraded,

     members of the Elks dislodged,

     magicians disillusioned,

     amputees disarmed,

     statues disfigured,

     calligraphers discursive,

     teachers detested,
     clerks defiled,
     bakers defloured,
     private eyes detailed, 
     law students distorted, 
     & dry cleaners depressed, decreased, & depleted?

And what about these oxymorons (or almost oxymorons):

Alone together

American English
Anarchy rules!
Bad health
Beginning Finnish
Business ethics
Cafeteria food
Civil war
Common sense
Constant change
Creation science
Curved line
Death benefits
Definite maybe
Dress pants
Extinct life
First annual
Friendly fire
Good grief
Government organization
Guest host
Jumbo shrimp
Living dead
Microsoft Works
Military Intelligence
Mutually exclusive
"Now, then ..."
Operating system
Peace Force
Plastic silverware
Same difference
Second best
Soft rock
Taped live
Tight slacks

Unbiased opinion
Work party

If you speak three languages you're trilingual. If you speak two, you're bilingual. If you speak one language, you're American----fishducky