If your friend shares a shocking piece of news or if you see something that is particularly surprising, then this emoji is usually a good choice. Let’s say your friend has an enormous secret about someone, a secret so shocking that it physically causes you to open your mouth in surprise - this is very likely an appropriate place to use the face. Usually, the face by itself is enough to show the surprised reaction - but in other cases you could highlight the shock with some additional text like OMG. In the case of something surprising but funny, you could used the Astonished Face followed by something a little more jovial.

Approved in Unicode 6.0, the Astonished Face emoji was added to Emoji 1.0 in 2015 - an update which saw many of the most used and popular emojis added including CWL Face and Grinning Face.