The word is a hybrid of the expressions "shit!" and "dayummm (as in damn)!". When used it means that the incident or anything that is being described is cringingly bad and amazing at the same time. Although the 2 words from which it originates is part of the american lingo, shiyum is popularly used in the medical colleges in south india.
Someone who is addicted to obtaining money and building wealth. A money addict and fanatic. Breadheads often work more than one full-time job, and some even participate in illicit activities to "obtain the bread".