A modifier plus 거 names a thing by a quality instead of a noun, and 주다 hands it over. 차가운 거 주세요 is how you ask for your drink iced — literally 'give me a cold one'. The pattern carries judgement easily: 나한텐 거지 같은 거 주고 complains about being handed a rubbish one, while 좋은 거 주는 거잖아 is giving someone a good one. ~ 같은 거 주다 means giving something of that general kind, as with 간식 같은 거.