:d
A wide, open-mouthed smile or grin. If the character also has one eye closed, it's also ;D.
The mouth should be flat-topped and the bottom should be round, like the letter D. For the opposite, an unhappy expression with a flat-bottomed mouth, see D:.
Actually ":D", in lower case due to technical restraints. For a ":d" expression with the tongue out, see :q or licking lips.
Examples
See also
This tag implicates smile (learn more).
The following tags implicate this tag: ;d and xd (learn more).
