Why do the words flammable and inflammable mean the same thing?
The dictionary at reference.com indicates that both words mean:
“easily set on fire; combustible.”
The prefix in- means not. The word roots section on membean.com says so. The page even has a cute little interactive tree with examples.
Call me crazy, but is seems to me that having two words that ought to have opposite meanings but don’t is just asking for trouble.
“Dude! That truck has a sign that says it’s inflammable!
Hold my beer and watch this!”
Not a good thing, unless you’re trying for a Darwin Award.
An onomatopoeia is a word “which imitates the natural sounds of a thing. It creates a sound effect that mimics the thing described….” 
Bees buzz, cows moo, horses whinny, etc.
However, there are some words that sound so much not like what they mean that you can get yourself in trouble using them.
For instance, the word pulchritudinous sounds more like the symptom of an infectious disease than a compliment. If you say:
“My, what a pulchritudinous woman you are!”
to your date, chances are you’re going to get slapped – even though you shouldn’t. Pulchritudinous actually means:
“having great physical beauty.” 
Huh? Who, how, and why, we ask ourselves, would someone come up with such an ugly-sounding word to describe beauty?
Inquiring minds want to know. 
 Source: literarydevices.net.
 I suggest you tell anyone you’re going to describe as “pulchritudinous” what the word means before you use it.
 And did he ever have a date?
Have you ever checked out at the grocery store and noticed that the clerk seemed to be paying undo attention to – or made too many comments about – your purchases?
Of course, you can be polite and pretend you don’t notice. Or you can ask the over-attentive clerk:
“Is this the right amount of toilet paper for this amount of food?”
Sometimes when a server delivers the food to your table, he asks a question that makes you wonder if you’re supposed to eat the food after that.
I can deal well with, “Is there anything else I can get you?” or even “Does everything look okay?”
The one that finally got to me was:
“Did everything come out okay?”
I turned around to look over my shoulder, turned back, looked the server in the eye, and replied:
“I don’t know; it hasn’t come out yet.”
You don’t have to wait long for someone to say, “Ew, gross!” when something is, well, gross.
That phrase is pedestrian in the extreme. You get the message, but there isn’t anything original or evocative about it.
The next time you see something, gross, try saying,
“That’s gross enough to puke a buzzard off a gut wagon.”
It’s both eloquent and evocative, and your friends will appreciate your eloquence, if not the mental image you just evoked in their brains.
“________ ain’t worth shit in a handbag.”
If you can think of anything more worthless, with as evocative a mental picture as that idiom, please share using the Submit Your Own
“Yes, she always did favor that horizontal mortuary look.”
“If a cat had kittens in the oven, you wouldn’t call’em biscuits, would ya?”
Why do the manufacturers of arthritis medication packge it in hard‑to‑open containers?
You’ll get one of two possible responses:
Either the answer you get will be a lie, or it will be the truth you don’t want to hear.
You’re going to get hurt either way. Don’t go there.