구 하다

casual -고 하다, mostly 'blah blah'

-구 is simply how -고 comes out in relaxed speech, so 옷을 입구 하는데 is 입고 하는데, 'wearing it and'. Most lines here are the set phrase 어쩌구 하다, standard spelling 어쩌고 하다 — 'going on about such-and-such', used dismissively about what someone says, as in 글로벌 경찰 어쩌구 했던 미국, 'the US that used to go on about being the world's police'. You will hear this constantly but should not write it anywhere formal.

Register: very casual speech