는구만

Well, would you look at that

It notes out loud something you have just registered, in a relaxed and slightly gruff way: he sings pretty well, the kids all know it from an early age, they are thorough about it. It does the same job as 는군 and 는구나 but sounds older and more offhand, the kind of remark an uncle makes. Several lines here carry a dry, needling edge, as with the one about somebody taking everything for himself.

Register: casual plain speech; sounds like an older speaker