"ist" is the combination of 'is' and 'it'.

"ist" is similar to, or the mere opposite of, "it's", which is a combination of 'it' and 'is'.

if (we're) still talking - used in the sort of super-heated relationship which might flame tomorrow

Full form : I see typing
Used when you just saw the other person typing but then they cancelled it. Used to force out something the other person is hesitating to say.

to the above mentioned.

what you get when you mistype its while typing online.

usually sounds better than its

The worst possible class you could choose as an elective in years 9 and 10, especial when the teacher has no idea what he is teaching (and even admits he has no idea), and the class ends up teaching the teacher. On top of this the curriculum is literally older then most high school students.

Ists = I swear to sucuk
It’s a word that the most ppl that understand Turkish use.
(Sucuk is a very popular food in Turkey)

Means Initial Strength Test, the entrance physical fitness test for the United States Marine Corps.