This is just a small question about colloquial German. Would you ever use the word 'was' when asking the equivalent of the English expression 'what?' as when a person has misheard a statement or is in disbelief? Because I've been taught that you should use either 'Was denn?' or 'Wie bitte?'
The reason I'm asking is that I see a lot of people who barely speak German using simply 'was' to mean 'what' and I think it's wrong but I'm not sure.