From Dictionary.com:
–noun
a printed punctuation mark (‽), available only in some typefaces, designed to combine the question mark (?) and the exclamation point (!), indicating a mixture of query and interjection, as after a rhetorical question.
Also, interabang.
Origin:
1965–70, Americanism ; interro(gation point) + bang1 , printers’ slang for an exclamation point