It is what you want it to be. 1.It can be condescending 2. It can be used to say goodbye 3. it can be used jovially.
1. Arguing or proving a point. You are frustrated and pissed off so you tell the person to "sukdik" in a negative tone. Similar to a fuck you connotation
2. You knuckle pound your buddy as you finish hanging out with the last words being "Later, sukdik!" Similar to the phrase "Later bitch!"
3. In any conversation at any moment the term can be used like any cuss word, if used in the right moment, it can be funny.