The interrobang is a seldom used question mark that expresses both surprise and a question at the same time, similar to the way people sometimes use a question mark and an exclamation point together in informal language, eg. "He did what?!"
Do you ever use interrobangs?
To be honest I only knew what they were called since there is George Hrab albumn called Interrobang. I do often use "?!" in informal writing but I have never been bothered to work out a keyboard shortcut to use an interrobang when typing.
I didn't know there was a term for it, but yes I often use it - especially in verbal conversations with others. It looks cool, and takes a bit of the load off of asking a question/making a statement :P