Originating from online fraud/419 scam used by fraudsters when emailing potential marks. Yahoo was the foremost email account used by them. Since its origin, the word is now used to describe the act of online fraud, a nigerian fraudster and the fraudster lifestyle.
"he is one of the them yahooze boys"
"My guy, how are we goint to eat?"...
"...ah ah?! yahooze now"