A combination of the words shenanigans and bonanza. Usually used to describe an incredible amount of shenanigans, or an incredible game of Shenanigans, typically involving a large number of people and several rounds with all sorts of punching and yelling.
Tom (after a 3 hour session of Shenanigans): Wow! That sure was a regular Shenanza!
Bob: Hey, Tom, let's go out to the bars, get really drunk and have ourselves a shenanza!
Tom: That sounds like a great idea!