🤦

 Facepalm  or 🤦 is a gesture in which the palm of one's hand is brought to one's face, typically as an expression of disbelief, shame, or exasperation.

mp4 video

Brainstorming
Eli Pariser in What obligation do social media platforms have to the greater good? (at about 11:55 into the video) suggests building in a facepalm response to other's social media posts to indicate a soft, negative social feedback. This could be in lieu of more drastic online moderated responses like banning, shunning, blocking, report abuse, shadow banning, or deplatforming.