What?! What‽ When should I use an interrobang?

GlyphsAn interrobang is a punctuation mark that combines a question mark (?) and an explanation mark (!). 
What?!
 It cost how much‽ Are they questions or explanations? Instead of typing two punctuation marks, you can type an interrobang.

If you’re preparing a print document, you can find 4 variations of the interrobang in the font Wingdings2. For web documents, type ampersand plus #8253; in the HTML code. But, the symbol doesn’t exist in most fonts on mobile devices.