That little stuttered nono is one of his favourite noises that Viktor makes. Right after his either considering or condescending (depending on the situation) eehn sound.

He is in so much trouble, isn't it?

Viktor is leaning close, and from this distance it's easier to see the flush in his cheeks and oh gods, okay, he has exactly one chance at this, and he absolutely needs to not fuck it up. So he works to rephrase what he said into something hopefully intelligent sounding and lands on --

"Just that if I wrote out the equation to measure the circumference of your waist, and compared it to the one measuring the span of my hands, I think they'd match almost perfectly."