Distraught Face, Weary Face
This is a frowning face, with its eyes closed and its eyebrows wrinkled. It seems that it is about to give up.
In most platform icons, the upper teeth are displayed on the face, and the tongue is displayed on some faces, showing that the mouth is wide open. Except au by KDDI and Docomo platforms, which depict purple faces, other platforms all depict yellow or orange faces.
This emoticon can be used to convey all kinds of depression and sadness, and sometimes it also means a playful sigh, which is similar to the meaning of "speechless".