Bulunmaz hint Kumaşi olsan ne yazar. Ben kot giyiyorum…

It was written under a cartoon, it seems to be funny but I don´t get it... 

"Bulunmaz hint kumaşı" is an idiom, literal translation is indian cloth (fabric) that is almost impossible to find. It is used to describe rare and precious things.

"kot" is denim, bluejean

I agree with ikicihan´s explanation.

"Who cares even if you are a rare/precicious/difficult-to-find Indian fabric, I wear jeans!" 

"Bulunmaz Hint kumaşı" (Difficult-to-find Indian fabric) denotes something rare and precious.

It is a fun way of saying, "You (or others) may be thinking that you are such a rare beauty, (attractive, irresistable, unique), but you are not my type, baby!

I often encountered "amk"

i think it means f***

It would be considered a vulgar or rude expression in Turkish, and is probably an abbreviation of amına koyayım (am = vagina, koymak = to put, to place)

It seems to be used as an expression of frustration from what I read here