When this happens irl, you say oO-Kay! Like in K-dramas, while emphatically forming oO with your mouth, and throwing up the 
okay sign 
After watching a kdrama where they yell, or say 그만네! (geu-man-ne!) - Stop it! or 멈추다! (meom-chu-da!) - Stop! a lot, you want to yell, or say it irl 
some other words or phrases that tend to pop in your head are:
- 먹었어? (meog-eoss-eo?) - You ate?
- 난 괜찮아! (nan gwaenchanh-a!) - I am fine!
- 알았어. (al-ass-eo.) - okay.
But, if you say these words out loud in Korean, no one would understand. Aaah! The language barrier