International Baccalaureate Program. An international academic program sponsored by Satan. It hooks in overachievers with the promise of college credit, then later explains that they probably won't get it. Most people in IB become bleached by their computer screens as a result of never going outside, find it normal to go without sleep for a week, and choose to study rather than eat. In the end they all look like zombies.
IB therefore IBS (meaning I Bull Shit or Irritated Bowel Syndrome... both occur often as a result of IB)