why do americans say y'al instead of you all?

That's an expression from the US Deep South. And it's a corruption of the words "You all." It has been around since before the Civil War. Don't know how it got started, though.

like you can kiss my grits .. now thats funny ...lol

Because Americans dont speak English

i love NCIS but NCIS New Orleans the actor Black does not speak English and the 2 Girls are Not Much better

where does anyone Get "Harris" From harassment

and a Rout is a Complete Direction of an army

A Router Shapes wood

and a Root in English is sexual Intercourse

A small section of America use this colloquial.

Every country and sections in the country have colloquials.

And it is y’all. Two L’s.  

Why does it make you laugh? How do you restore the second person plural that English lost around the 16th century? In parts of the US, people use "you guys". In New Jersey, they say "youse" which is logical, but connected with a lower socioeconomic group. In the South, they say "you all" often contracted to "ya'all" which seems to be spreading, as the most elegant way to make "you" plural and communicate clearly. 

Most Americans never say "ya'll" (except when imitating Southerners).

It's primarily people from the Southern States that employ that slang term.

https://en.wikipedia.org/wiki/Y%27all#Regional_usa...

A contraction. Similar to can't or didn't or you're etc.

it's just shorter...................

theyre just trying to make it shorter