Why do Americans say "like" so much?
It's kind of a linguistic habit, I guess. I don't even know what it means. I don't have a definition for the specific use of it, and I don't even know where exactly it should be used. I say it too, unfortunately. I have as long as I can remember. It seems to be part of the dialect nowadays.
Why do some Americans say "y'all"? Where does it come from?
Some of us say y’all because English lacks a standardized second person plural pronoun. Different dialects use different standards. Not all people in the US use y’all, and I’ve never met a person from Canada who did. It’s actually much more nuanced than all of us using that.California English, which is the defacto standard for broadcast purposes, follows the BBC model of using “you” for both singular and plural.Some people in Pennsylvania use “yin” instead of “y’all”. I’m unclear on the origins of this.Some really thickly accented New Yorkers use “Yous”, optionally followed by a clarifying noun.Some people say “you all”.In the southeast US, “y’all” is the standard.I personally prefer y’all out of these because its possessive form is not an exception to the standard rules: “y’all’s”. In most nouns in English, creating the possessive form merely requires an apostrophe and an S. But some words like “you” have exceptions like “your”. I don’t care for these, hence my preference for “y’all” due to it being standard. Additionally, “all of y’all” can be used to address multiple groups of people. It’s kind of like recursive plurality, which is useful on occasion.
Why do most Americans say brand names so much instead of the generic name for a product or service?
Because if I said diphenhydramine people in America would be like WTF are you talking about?So, I say Benadryl and then the clerk at the cash register says, aisle 3. Sadly, you have to dumb it down for most kids in America who are working the manual labor jobs. The attitude in the current generation is: Get it done and don’t worry about the details. This is sadly encouraged by the companies here. I cannot tell you the number of times I’ve heard, “Don’t worry about the quality. You need to increase the quantity.” In generations before, quality was important because it translated to more sales. Now, more marketing translates to more sales and the ignorant populous eats it right out of the hands of the companies which feed them.
Why do americans say sayonara?
It's just a borrowed word that pop culture picked up. It sounds nice, so we say it. XD The Japanese are actually a wonderful example of borrowed words. A great deal of less common things in Japan are referred to using words from different cultures (lion is raion, music box comes from a dutch word I can't remember, etc). The same thing applies to the American use of sayonara.
Why do most Americans now say ben instead of been they don't for example say sen instead of seen.?
This is the kind of question that makes me glad I'm a native speaker! I don't know why we say "ben" not "been". Custom, I guess. For example, I live in Boise, ID. We pronounce "Boise" as "boy-see". But, there's a city called Boise City in Oklahoma that is pronounced "Boys" like noise, which makes a lot more sense because a name that is spelled like "noise" except for one letter ought to be pronounced like "noise". Good luck with this one! :)
Why do most Americans pronounce "T" a "D" ?
Matsumoto Kogyoku is right, and "waiting" is a great example. Because of the position of the tongue in the mouth partway through the word and the position it needs to take to make a "t" sound versus a "d" sound, it's sometimes easier and smoother-sounding to pronounce Ts as Ds. Some parts of the country do this more than others. That's part of what makes a regional accent. Where I'm from, the people will really heavy local accents make a lot of Ts into Ds and make a lot of long vowels into short vowels and often skip vowels near the ends of words that end in n's. Normally, I speak pretty proper English, but when I'm around a lot of the old guys from my town and "her thim get ta' talk'n 'bout ther days work'n in the still mill 'cross the crick and watch'n the Stillers aft'r supp'r" I pick up their accent.
Why do some Americans say “I could care less” instead of “I couldn’t care less”?
I really like coming up with good rationalizations to these. One of the things that’s so fun about English is that our meanings and paths have drastically more ambiguity to them than many other languages. So for instance:“I could care less”Has a very different meaning from:“(Pause, thinks) I could care less”As if to say:“I thought about it. Really critically examined the question and have realized that while it might be difficult, it is in fact possible for me to care less about this than I currently do. I would be hard, because I care so little about this (which is why I paused. I had to think about it. But I’ve decided that it is theoretically possible.”See, the important thing in this context is not that you literally couldn’t care less. That’s obviously an exaggeration. The important thing is that you care so little that it was actually a question. It wasn’t immediately obvious that it was possible for you to care less than you care about this particular thing.So, my personal interpretation is that we say this because we’re bigger fans of wordplay than exaggeration. I do think that’s pretty consistent in English. We definitely have a bias toward subtle wordplay, and away from exaggeration and puns. Primarily because this kind of vagueness is exactly what English is good at.