이게 어딜 is colloquial Korean, which often means it doesn't translate into English. It means something like "how dare you (challenge me)...!". You have to be careful about using it on people because it's insulting to refer to someone older than you as "이게"(this thing).

이게 = This 어딜 = Where In English "이게 어딜" means = Where is this

이게 어딜 = This is where .... (something happened)