Remember this colleague?
As he works in a fairly similar area to me, I had to talk to him about taking on one of my students while I am away - my boss had decided he would do it, it was just a formality, and to be honest I would have preferred just to speak to the student and leave information for the colleague until the last minute, on the need-to-know principle. He didn't really have a choice about doing this.
But to be polite, I told him what was happening and why, and he asked "so, are you adopting from the UK or overseas?" Fair question, since we both know Overseas Adoption Colleague and her husband, of course. "Overseas" I say. "Oh, which country?" "The US" I say.
Giggle. "That well known developing country?".
I managed to bluster something about the country not having much to do with whether a child needs adoption or not, but really? If you know nothing, is it not wiser to keep quiet.
Hopefully he has at least taken on board the warning that the information is not for sharing.