Mum's The Word

I have thirty-ish friends who went to Oxbridge. One of their pals was recruited by the Security Service while a student, and works there still. He has of course asked all of his friends never to refer to the fact that he works for you-know-who.
On a family occasion the spook was horrified when a friend's slightly flaky mother sounded as if she was about to out him. His panic subsided when he heard what she actually said:- "Say hello to Gavin. He works for - erm - MFI".