This might be a case of artificial intelligence becoming too smart for its own good. It was reported just recently that a well-placed feature in Google Calendar that tries to be smart about the events that you create can actually lead to some embarrassing situations and send invitations to others even for private events.
Google Calendar uses an amount of natural language processing to intelligently discern the events that you're trying to create. Based on the event text, it can automatically add the date or time, add people to the event's guest list, or even the location a map. To be fair, this feature is documented in in Google's help pages. Unfortunately, that documentation is a bit sparse and doesn't really explain the implications.
It appears that given a certain combination of factors, people whose email addresses appear in the event's text might be sent an email about the event. This happens automatically without the user knowing it and even when the event is marked as private. It doesn't happen always though. It seems to occur only when creating an event from the full editor and only when using Google Calendar in a web browser. Android users seem to be safe from the bug. At the very least, it won't send out an email but it will add the event on the other person's calendar. This can lead to situations where another party gets informed of a secret event, which may or may not be a good thing.
While it may seemingly be a harmless feature bordering on an annoyance, a few enterprising, not to mention malicious, individuals can easily abuse that feature in order to spam people. Google is said to be working on a fix but in the meantime, the only workaround is to avoid putting email in the event text and use the person's name instead.
VIA: The Verge