An American, Martin K. Speckter, conceptualized the interrobang in 1962. He was head of an advertising agency and believed that advertisements would look better if copywriters conveyed surprised rhetorical questions using a single mark rather than a question mark (interrogative point) and an exclamation mark or point (known in printers' and programmers' jargon as the "bang").
If you are using Microsoft Word, you can type an interrobang by switching to Wingdings 2, holding shift and typing 6^. Sadly I think the only way to use it on social media (at present) is to copy and paste a photo.
For more information on this funny little symbol and its inventor check out http://www.interrobang-mks.com/