Usually I'd just reply, "Well, it's your face that's killing me. Your very existence is offensive."
A guy at my work continually gave me crap about mine messing with his allergies because of the smell. Saying I was smoking and putting bad chemicals in the air and all sorts of garbage.
This went on for a couple weeks before they called me into the general manager's office along with 2 managers. They told me that the guy and several people had complained about it because of messing with their allergies and they complained because the fda hadn't approved them.
They asked if there was something else that I could do. So I told them about flavorless/odorless and they said that would be great. So I got that and the dude still complained. This went on for around another week. So then my manager pulled me to the side and said if I needed to vape just go in his office and build a .... if I needed to, smoke it out. Just as long as I did it in there. I agreed to it. The dude still didn't like me doing it but there wasnt much he could do about it then.
A few days after that we had a meeting outside. I was standing by myself 30 ft away from the guy and he started up again that this was a no smoking area and that I couldn't do it around him. I lost it. Absolutely lost it. I blew up and told him that he could f off and if I heard another thing from him about it I was going to knock him out. I had done everything asked of me, but the dude was an ignorant useless human being and I had had enough. After having several guys pull me away to keep me from even getting to him. The guy came and apologized to me for being an ....
Since then I have been happily vaping away in my bosses office. I'm actually writing this from his office right now.