Guni's examples are great, I'll just add some extra information to it. 됐거든 is an ironic expression to mean you refuse to take anything worthless such as a lame excuse, bad joke, big talk, patronizing offer etc. 되다 is probably the most idiomatic verb, it means: 1. It's completed. (B is fixing A's broken computer) A: 아직 멀었어? B: 다 됐어. It's completed. 2. It(or everything) is okay. (after making a lot of effort not to apologize first) 알았어. 미안해, 내가 생각이 짧았어. 이제 됐어? Okay. Sorry, I was careless. Is everything okay now? *이제 됐어? could put you in trouble if you say it in a situation where you did something wrong. (B is sulking) A: 삐졌어? Are you sulking? B: 됐어. It's okay. (a pouty expression on her face) 2. It's ready. - 저녁 다 됐어. Dinner is ready. - 다 됐어. I'm all set. 3. (Time) is up. 시간 됐어, 가자. Time's up, let's go. 4. Enough. (A's being caustic) B: 됐어. 그만해. Enough. Stop it. Essentially, without an object 되다 means 'to become(reach) something ideal/ultimate'. So it is used as those above. Let me take another example, we say "못 됐어" when talking about someone nasty, meaning they didn't reach a certain standard that we think people should. -거든 is used to inform someone of something. With 됐거든, you're speaking as an informant. "I inform you that it's okay", but it's not okay in fact - this is why 됐거든 sounds sarcastic and a bit cynical at times(with your tone, facial expression) 됐고 sounds neutral. - 됐고, 잠이나 자. Enough, just get some sleep. 됐네 sounds friendly. 이제 된 거 같네, no? ^_^

됐어! / 됐거든! It's sort of 'never mind!' Situation 1 For example, A : Would you help me with this homework now? B : I'm busy now. I'll do later. (But it seems that B's work is not important enough to refuse A) Few hours later. B : What's your homework? Let me help you. A : (됐거든!/됐어!) Never mind! (A was disappointed and angry at B's inconsideration. So A DOESN'T WANT B's help anymore.) Situation 2 A : I don't know what I did wrong? B : Really? A : No! I don't! Don't blame me because of your fault. But later, A realize that it was his fault and try to apologize to B. A : I'm sorry. B : (됐어!/ 됐거든!) ( B is still angry at A, and DOESN'T WANT to accept A's apology now.) This is my limited explanation of "됐어/ 됐거든" in English. I hope that it will be helpful.

Alright, i looked through some of the tv-shows where i've heard it before and they spelled it out as 됐고, not 됐거. It was used to interrupt a conversation and the translation this time was "Enough!". Still, if you have some more info i would appreciate it. Because i can't find anything about it on google.. ^_^

After some googling it seems like it is spelled 됐거/됐거든. Still wondering how/when it is used though. ^_^