Google+ Events launched on day of Google's I/O 2012, as an alternative to services like Evite or Facebook's Events, comes under privacy attack. In the +Events by default, other people have been able to "invite" you to events, which in turn automatically showed up on your Calendar - "even if you had not yet confirmed that you would be attending," that resulted in some users getting invitations to dozens of unwanted events from people they barely knew.
G+'er Wil Wheaton who made a public stink about the situation says, "To be clear: People who I have in a circle can send me an event. People who have me in a circle, but who are not circled by me, can not." Others say they have been "relentlessly spammed by strangers."
Here's an example of some really awful event spam -- Notice the spammer invited Sergey Brin, Larry Page, and Linus Torvalds!:
Wheaton, now reports that Google's SVP Vic Gundotra has responded and will be working to fix the issue soon. Gundotra replying to Wheaton's complaints, stated:
"We are doing exactly what you requested. We should have contemplated and anticipated how people would abuse this and how painful this could be for celebrities with large followings.
We have pushed a number of fixes yesterday (some were bug fixes that showed up at scale). Expect more fixes today. Sorry for the trouble Will."
In the meantime, you can take matters into your own hands. Head into your Calendar settings, and turn "Show event's you've declined" to "No," then switch the "Automatically add invitations to my calendar" setting from "Yes" to "No, only show events to which I've responded."
That will stop the influx until the changes Google is promising roll out to everyone.