O.o
The two different sized eyes indicate this person is completely confused. It comes from cartoon animation, where the eyes change sizes back and forth when a character is perplexed.
:-??
The question mark for a mouth indicates the person does not understand something.
:-/
This emoticons can also mean perplexed or frustrated.
:-\
Sometimes can be used to mean perplexed or frustrated.
:\
Means the person cannot decide one way or the other.
:/
Means the person cannot decide one way or the other.