嬉し泣き

A yellow face with a big grin, uplifted eyebrows, and smiling eyes, each shedding a tear from laughing so hard. Widely used to show something is funny or pleasing. 

Named the Oxford Dictionaries 2015 Word of the Year, and the most used emoji on all platforms from 2011-2021. Briefly overtaken as the top emoji on Twitter in 2021 by 😭 Loudly Crying Face, though as of January 2022 it has reclaimed its top position on the platform.

See also: 🤣 Rolling on the Floor Laughing which expresses more intense laughter; or cat variant: 😹 Cat Face With Tears of Joy.