A Refrigerator That Makes Its Own Ice Cubes‽
The interrobang was a new kind of end mark. It denoted a question that expressed surprise or incredulity. This also made it useful for rhetorical questions, most of which are also incredulous. In his article, Speckter was already envisioning exclamatory-slash-rhetorical advertising slogans that could take advantage of the new mark, such as “What‽ A Refrigerator That Makes Its Own Ice Cubes‽”
Recently I revisited the Interrobang episode on 99% Invisible, and it is a pure delight.