개이득 /gae-i-deuk/
Insane gain / Crazy good deal
Combines 개 (intensifier) + 이득 (benefit/gain). Used when you get way more than expected from a deal, situation, or stroke of luck.
Examples
1+1 행사에서 개이득했어
Got an insane deal from the buy-one-get-one sale
공짜로 받았어? 개이득이다
You got it for free? That's an insane gain