The Old Vic is showing a new play called "A flea in her ear". I say new but it was actually written in 1907 by Georges Feydeau. The play is a translation of a French Farce and from what the reviews are saying it's worth going if that's your cup of tea.
What interested me was the phrase, "a flea in her ear", according to one user on WordReference it's an old idiom going back to at least the mid-fifteenth century. Yahoo answers suggests, the real meaning of "mettre la puce à l'oreille" is "to arouse someone's suspicion", "plant the seeds of doubt", which sounds about right. There are suggestions in the press that the phrase is connected to "bee in her bonnet" which I have to disagree with although the free dictionary does suggest an alternative use of that phrase which is consistent with "A flea in her ear".