Little details that show shock
The Greek letter Σ placed before a face is a manga shorthand for a sudden jolt, as if the character just jumped. Vertical lines like ||| under the eyes suggest someone turning pale, and a stray ; or 〃 adds nervous sweat. Mismatched eyes, as in (o_O), signal confused disbelief rather than simple amazement, so you can fine-tune exactly how stunned you feel.
Good moments for a shocked face
Surprised kaomoji work well as instant reactions: a friend announces an engagement, a show ends on a cliffhanger, or your inbox suddenly fills up. They also add drama to everyday surprises, such as discovering that it is already Friday. For happy shocks, try sparkling eyes like (✧Д✧); for awkward ones, a sweaty (゜o゜;) says it best.