ok i know its prob old hat but,

anyone really know how (and why) cities celebrate. ok, yes their happines muct be high..but how how. and how random an event is it. very goodwhen have corporations as cities have :) NO maintenance. anything else im missing?

You mean "We love the xyz day"?

It randomly occurs in cities that are size 8 or greater, have no angry citizens and aren't losing food due to unhealthiness.

so its completely random?