Just adding that while this is often used by ESL and native speakers as Jeff said (an expression of confusion, puzzlement, or even frustration caused by confusion), it's definitely not standard English and one wouldn't use it in, say, an academic paper or even a workplace email.
Fun fact: Once upon a time, there was a mark that combined the "?" and "!" symbols called the interrobang--"interro" being the root for "question" (as in "interrogation"), and "bang" being common journalistic slang for an exclamation point. It didn't stick, but it definitely looked cool: http://en.wikipedia.org/wiki/Interrobang