Only a true Texan knows the difference between a hissie fit and a conniption fit and that you don't "have" them, but "pitch" them.
Nobody but a true Texan knows how many fish, collard greens, turnip greens, peas, beans, etc. make up a "mess."
A true Texan can show or point out the general direction of "yonder."
A true Texan knows exactly how long "directly" (sometimes pronounced dreck-lee) is - as in "Going to town, be back directly."
Even true Texas babies know that "Gimme some sugar" is not a request for the white, granular sweet substance that sits in a pretty little bowl in the middle of the table.
All true Texans know exactly when and what "by and by" is. They might not use the term, but they know the concept well.
True Texans know instinctively that the best gesture of solace for a neighbor who's got trouble is a plate of hot fried chicken and a big bowl of cold potato salad. (If the trouble is a real crisis, they also know to add a large banana puddin'.)
True Texans grow up knowing the difference between "right near" and "a right far piece." They know that "just down the road" can be 1 mile or 20 and they understand "kiddy corner" and "kaddy cornered."
No true Texan would ever assume that the car with the flashing turn signal is actually going to make a turn.
True Texans know that "fixin" can be as a noun, verb, and adverb.
True Texans make friends standing in lines. They don't do "queues," they do "lines." And when they're in line, they talk to everybody.
True Texans never refer to one person as "y'all" and never spell it "ya'll."
Every true Texan knows tomatoes with eggs, bacon, and grits are perfectly wonderful; that red eye gravy is also a breakfast food; and, that fried green tomatoes are not breakfast food.
Texans say "sweet tea" and "sweet milk." Sweet tea indicates the need for sugar and lots of it - we do not like our tea unsweetened; "sweet milk" means you don't want buttermilk.
And a true Texan knows you don't scream at little old ladies who drive 30 on the freeway - you say, "Bless her heart" and go your way.
-----------------A Final Thought ...
"If a man’s from Texas, he’ll tell you. If he’s not, why embarrass him by asking?"
- John Gunther (1901–70), U.S. journalist