This one has always puzzled me, ever since I knew a family by the name of Tooth. One at a time was no problem – Mr Tooth, Mrs Tooth, daughter Tooth … But when they all turned up together, I could never determine whether I should call them ‘the Tooths’ or ‘the Teeth’. The former seemed grammatically incorrect; the latter may have given the impression that I was not showing due respect.  I guess I should have asked.