This page is about different ways English people ask to repeat when they have not understood what the person in front of them has just said. Luca Capello started the discussion on the debconf-discuss@ mailing list and Tim Retout provided some UK expressions.
 US English
- Say what?
- What's that?
- Say it again
- Whatcha talkin bout Willis . . .
 UK English
 basic responses, in descending order of politeness
- Come again?
- Say Again! (this is UK Army radio-speak -- the reason being that the word "Repeat" is used for indicating that the last artillery barrage should be repeated, which, if you've moved forward in the interim, is a great way to get yourself killed, so use of the word "Repeat" is strongly discouraged) -- Fil
 more elaborate responses for bonus points
- I beg your pardon, what did you say?
- I'm terribly sorry, come again?
 more self-deprecation and explanation
- I'm afraid I didn't quite hear, would you mind awfully repeating that please?