a smiley used in e-mails, instant messages, etc. there's one pair of eyes but two mouths. used when very happy/sad/any other emotion. usually looks something like this:
you can make them sad too.
person 1: that's hilarious. you're soooo funny!!
person 2: (:)
person 1: ???
person 2: that's a smiley sandwich! DUH.