Google Calendar Phishing
Google calendar users.... an old phishing scam is back (actually it never left). If you see an event in your calendar that you did not ask for, it's a good reason to update your google calendar settings.
It's easy to do. Just click on settings while in Calendar, and scroll down to the "Automatically add invitations to my calendar" row options. Then select "No, only show invitations to which I have responded."
Sometimes, you might see a corresponding email tied to the calendar invitation. Spam filters can sometimes catch those, but if your settings say "Yes" to "Automatically add invitations to my calendar," the invitation will still make it into your calendar.
You should also be wary of unsolicited or unexpected Google Docs invitations. Here's a good article on this from May 2017.