I believ the technique you are thinking of colloquial (informal) language; Example
"1. I'm gonna go down to the beach. You wanna come?
I am going to go down to the beach. Do you want to come?
2. Ain't that strange?
Isn't that strange?
3. Ain't these doo whoppers unusual?
Aren't these things unusual?
4. I dunno where we're meeting up tomorrow.
I don't know where we're meeting tomorrow.
I do not know where we are meeting tomorrow.
5. Danny was as tough as nails. Danny was very tough."
All examples from [link]