Abbreviation for "injecting drug user," any drug user that injects their drugs intravenously with a needle.
IDU's should never share needles.
by avergonzado August 09, 2010
A short way of saying 'I don't understand' it was first founded by. Josh A Daniell
Do you know if she'll go to the mall tonite?
by Josh A Daniell March 30, 2015