제 한국친구가 저한테 그냥 "뭐더라구"라구 말했습니다. 무슨 뜻입니까?
Sorry~ lol I forgot to add the English translation ^^;; anyways, we were talking Korean and I thought this was what she said. Maybe it was 뭐드라고 not 뭐더라구~

Question

제 한국친구가 저한테 그냥 "뭐더라구"라구 말했습니다. 무슨 뜻입니까? 
Sorry~ lol I forgot to add the English translation ^^;; anyways, we were talking Korean and I thought this was what she said. Maybe it was 뭐드라고 not 뭐더라구~

Answer

As Hailey said, need more information to make it clear, but 
here is my theory. 

1) "그게 뭐드라고 하던데.." meaning "뭐라고 하긴했는데..." 
You saw or heard something, but you can't remember what exactly it was or it could be beyond your knowledge. Anyway it is something like you can't explain it exactly. 

2) It sounds like a dialect to mean "뭐하려고?" or simply "뭐?" or "뭐라고?" 
A:(Somebody's speaking in Jeju dialect) "blah~blah~" 
B:(I couldn't understand what it was, so that you can say) "뭐라고?"(뭐드라고?) 

Just my two cents.:)

Answer

This needs context...

Evden çıkmadan dil öğrenme fırsatını kaçırmayın. Deneyimli dil eğitmenlerimizden oluşan seçkimize göz atın ve ilk dersinize şimdi kaydolun!