Thank you.

'amn't' is new to me. I have not heard of this before. But I am not socializing as much and as widely as before. I must have missed many many modern words ;-)

I have heard of "a r n ' t" (อ๊าน ทึ) and "a i n ' t " (เอ๊น ทึ) - both are used to jokingly or in emphasis style to mean 'be NOT' eg.

- I arn't going/I ain't going = i AM NOT going.

- You arn't him/You ain't him = (But) you ARE NOT him (so you cannot do like him).