다니깐요

'I'm telling you!' — polite but fed up

-다니깐요 says something again with feeling, because the speaker feels they have not been believed: 아우 나쁘지가 않다니깐요 'I'm telling you, it's not bad at all.' The 요 keeps it polite while the tone is anything but calm — 나 진짜 안 훔쳐갔다니깐요?! 'I really didn't steal it, I said!' It is the casual pronunciation of -다니까요.

Register: polite but exasperated