Veterans, what is a good comeback for when someone asks “Have you killed anyone?”?

“Heh... heh... heh! It’s been quite a while. But an opportunity might have just presented itself now.”

Tell them they will know when this conversation is over.

Point to medals and reply:

'They don't give you these for making toast.'

No, but I am about to. That is the best answer

Osama

Tell them you'll answer tomorrow.

When I have been around someone that was dumb enough to ask that of someone else or myself I just tell them that its not polite to ask about such unpleasant things. Memories of things like that as well as other bad things haunt veterans and asking them about it just brings those demons back to continue haunting many of them is what I say to people when asking something like this. That has always been enough of an explanation for they and the conversation to move onto something else.

"So tell me, what sort of jackass asks that?"

"Lately?" and laugh

Tell them it's rude to ask a veteran that.