Who uses ?
The thinking face was added to the Unicode emoji set in 2015. It has widely been used as the emoji equivalent of “hmm” in any and all contexts that this might be used, from a literal thinking sound to a more abstract expression of skepticism.
Sometimes the thinking face emoji is used literally to append questions, and this shows the writer is contemplating an answer. In these cases, it is often paired with a thought balloon, or a light bulb. These questions often call for answers, and are statements of either confusion or consideration.
Other times, the thinking face emoji is used to cast doubt (though not necessarily shade) on a person or idea. Here, the thinking face emoji is more sarcastic in use. Soon after the thinking face emoji’s introduction, New York magazine’s Max Read explained it as conveying a "furrowed brow," an "alarmed murmur," or "concerned skepticism."
In these cases, it usually follows a rhetorical question, or even a non-question, adding a nuanced tone of doubt or passive aggression to the comment.
Sometimes the thinking face emoji is used as a stand-alone response to convey skepticism. In this way, even previously neutral statements can be altered by the thinking face emoji.
People who use the thinking face emoji are primarily young, though its use is widespread and international.
“If your 'friends' only support you when they see you doing good, are they really your friends? ”
TGTracks @tgtracks Twitter (March 18, 2017)
I don't think his album is that hot tho it's just average
Mimi @mjxmt Twitter (March 18, 2017)
I don't recall being like that at that age.
kleo @j0weezy Twitter (March 18, 2017)