Over time, emoji meanings have become subjective, depending on a message's context and wider cultural trends. Which shaking smiley face should you use? Is there a difference between each ...

Of the six billion emoji that are sent globally every day, around 70% are emotion based – for example, smiley face, love hearts. A smaller proportion of the emoji sent are sad expressions.

When Higgins tweeted Tuesday night for the first time in two weeks, it was just an emoji of a blue cap. What did it mean? Nobody knew, but the tweet had more than 500 replies within 20 minutes.