Green’s Dictionary of Slang

1. (US) one hundred, e.g. dollars .

2001		T. Egan Down Tick 65: The “6” was a flat two-hundo with another $125 added on to the bill for course materials.
2012		M. Lacher On the Bro’d 77: ‘You’re going to blow a few hundo on your dad? He’s like rich as fuck!’.
2013		N. Knight ‘Not Even a Mouse’ in ThugLit Nov.-Dec. [ebook] ‘Say…three hundred? [...] Three hundo's fine—believe me’.

2. (US, also hunj piece) a $100 bill.

2004		J.A. Juarez Brotherhood of Corruption 227: ‘Can you give me change for this hundo?’.
2014		C. Eble UNC-CH Campus Sl. Spring 2014 8: HUNJ PIECE — /h?n?/ one hundred dollar bill. Also HUNDO.