Kiri is a sound effect which expresses "serious," but attached with it subtly is a sense of obliviousness to circumstance. So kiri + yukkuri has that added stupidity to it which should be expressed.
dead serious stupidityAftah you bwing cyute Reimyu a woch of swheet shweets, punish dat schum oba dere!
Huwwy ich up!
Aftah dat, wick wick cyute Reimyu unchil she is aww cwean!