it is a way to change "verbs" to "noun" form. here is example conversation. A : 그 영화 봤어? have you seen the movie? B : 나 봤어 Yes, I have. C: 나도 봤음 , me,too ( usually, 나도 봤어. but C changes 봤어 to 봤음 ) I did homework 숙제를 했어요. - 숙제 했음 she took a shower. 그녀는 샤워를 했어요(했습니다) - 그녀는 샤워했음 he played a game 그는 게임 했어요(했습니다) - 그는 샤워했음 it is kinda abbreviation ~ 했습니다(했어요) in my case, 했습니다. 했어요 are too long to write, when i listen to lecture. 공부했음 밥 먹었음 잠잤음 kind of note taking for lecture. But in these day , many people use ~했음 in conversation. because of the culture of chatting and texting. it is a simple way to say and write. I hope I explain it well. Good luck to study in korean ps. I heard ~했음 form a 9 year old girl today. XD

Girls are usually using like this sentence during sending SMS or Instance message. Korean OPPAs should like to listen to if you talk using these sentence. It sounds cute!!! :)