Knuckles had expected a negative response, initially. After all, there was something about Lanolin that you didn't wanna screw around with. But when he saw the response, the follow up picture knocked the poor echidna off his ass. He'd never really had a sexual encounter before, and skin wasn't something that deserved that sort of flaunting (at least, that's what he always believed).
So why now, of all times, was this making him so damn flustered?!
How to respond back? Think, think, think!
[Txt]: Oh
[Txt]: That's a really nice picture
[Txt]: Once again, sorry about the flash, I got dared to take a picture, fiddled with the buttons
[Txt]: ... Is it okay to say I think you're really attractive?
He spent a long time trying to think of what to say after the apology, or how to react to her image. He hoped the question would drive the point home that saying 'nice' about her picture was just him trying to act respectful.