what are you wasting time doing?An impatient or scolding way to ask what someone is doing, often implying that they are taking too long or wasting time. มัว adds the sense of lingering or being occupied unnecessarily.
TH: มัวทำอะไรอยู่ รีบไปกันเถอะ เดี๋ยวสาย
EN: What are you wasting time doing? Come on, we're going to be late.