I’ve always interpreted the iOS grinning face as “anguished clenched-teeth look of constipation”, so it’s interesting to see how the same emoji on other platforms is actually interpreted as more happy.

The most widely misinterpreted is the “grinning face with smiling eyes” emoji, which—depending on the platform—can range from the rosy-cheeked cherubic face of glee to the anguished clenched-teeth look of constipation.

Source: That Emoji Does Not Mean What You Think It Means