To put on an act seeming to remove one's own stomach contents by means of forced regurgitation, such as eating something that makes you sick.
Alan: Hey man, I think Jimmy's faking it.
Jake: Why do you think?
Alan: He said last night that he had to heave bread, that he might not be in for school today
Jake: I think you're right. Why wouldn't he be able to come in if he threw a loaf of bread?