I used to say 'what?' but my mother always said "pardon me, I missed that" or some variation, and I made a concerted effort over the course of a year to replace the 'what?' The problem I have with 'what' is that it is so ambiguous, it could request 'what' someone said, 'what' they are talking about, or be a general statement as to your negative perception of their intelligence relative to your own. The ambiguity combined with the nasty slant seemed to me to be rather rude, especially as the 'what?' is an abrupt interjection. ~ H