Clean way of saying "motherfucker"
Usage in amongst K-pop fans most likely stems from entertainer Boom who used the phrase on episode 3 of 2PM's Idol Army.
Cast thought he said "motherfucker" in poor English and he stated he said "omma appa" and not a bad word.
An explicative that implies that it's denotee is both a mother and a father; which is at this point a medical impossibility. It is also used idomatically because of it's close relation to the word mothafucka. The word has gained much popularity in conjuntion with the latter: chinese dentist.
Kimberly: Would you help me with the clasp of this necklace? Oww! you just pinched me you mother father.
or
Stuart:This boat detailing job is getting to be a real drag.
Monty: Sure as shit is. Let's ditch these rich ass mother father chinese dentists and go rollerblading or something.