shortened version of "i dunno", which is a shortend version of "i dont know", which is a shortend version of "i do not know"

Mercury retrograde is the act of taking a shit whilst mooning one or more human beings. Your day can typically being going well, according to your horoscope, until you are forced into witnessing Mercury retrograde. Performing Mercury retrograde will often speed the astrological cycle forward for the individual performing the Mercury retrograde, bringing about happy and fruitful times to come.

Basically the same thing as iunno, it is a quickened version of "I do not know", used in both chatting and in informal speech.

It's history may trace back to Homer Simpson, who often makes a sound that is in between "iono" and "iunno". (Says a lot about his intelligence, doesn't it?)

12 year-old internet chatter's way of saying "I don't know."

retarded way of spelling i don't know

Slang for "I don't know"

This is the slang version of the phrase, "I don't know?"