We were sitting in the lunch room, chatting and enjoying our lunch. I was cutting a nectarine, while a co-worker of mine was giving me a hard time. We'll call this one CW1.
CW1: You know, if you crack open that peach pit there's a little almond inside.
Me: Yep, I discovered that a few years ago when one was already split open. Neat, huh.
CW1: You can eat it, you know.
CW1: Yeah, I ate it. It was a bit bitter though.
Me: You do realize those are full of cyanide, right?
Me: Yeah. Cyanide.
CW1: No way, I'm still alive!
Me: Well, one probably won't kill you. Just don't go eating a handful of them and you'll be ok, but it's probably wise not to eat them any more.
Me: Actually, that gives me an idea for a chemistry experiment.
(At this point, you should know my co-workers are aware of my chemistry hobby.)
CW2: OK, You scare me now.
I then go on to explain how there's a pigment called Prussian blue, which I've created before using Sodium Ferrocyanide, and so on, and that I'm aware of a way of extracting this pigment from peach pits, just as they did ages ago.
At that point everyone looks relieved; and I haven't even explained how non-toxic the pigment is, even though it contains the cyanide ion.