In fact, 囧 is used all over China (and Taiwan), and can mean almost any emotion. Look here
It can mean a response to something funny, awkward, or embarassment... Or you can 囧 just when you feel like it.
Because 囧 (or 冏, or any part resembling a face) can be a part of many characters, people use many other characters (many of which rare) as the "different forms of 囧".
崮 is the king of the 囧 Kingdom
莔 being the queen
囼 lacks the eyes
and 圙 is a wrinkled face.
商 is one of the "forms", with a hat.
Here is a tongue twister about 囧:
(God I'm obsessed with 囧, it's so 囧)