Coming from the 2005 film 'Dirty Deeds' which says 'IAB'
IABS is a clearer way of saying Its all bullshit
because IAB could mean 'I am bored'
Person two: "Na man, IABS, She was with me the whole time"
It's what all of M's friends call her, and was first invented and used by the effulgent Zorbalicious.