I've often read/heard writers say that they got an idea for an article or story by something that they saw or overheard. This has never really happened to me - not directly anyway.
I was in the hairdressers and I was sitting waiting for the colour to work it's magic I was flicking through magazines not really reading about people I've never heard of who are famous for God knows what reason. The radio was on and the presenter said something and it was like a light bulb going on over me head and I thought "Yes, that would work."
I'll let you know if anything comes of it - or rather when something comes of it.