Are You Talking To Me?

Can you people tell me more about famous filmy quote 'Are You Talking To Me?'
In what context people use this line?

Thanks
SB

It's from "Taxi Driver" -- www.msu.edu/ user/svoboda1/taxi_driver/sounds.html

In my experience, it's used by most people as a goof. In a humorous fashion.

That's interesting because in my experience it is used as an aggressive challenge: the implication being that if 'you' are talking to 'me' there will be trouble.

DFG