Session Hacked by Participant who raised OTHER PEOPLE'S Hands

Next thing I know is I'm hearing the Andy Griffith TV show theme song over top of the song I'm sharing.

THEN, I'm seeing participant's hands going up, one at a time (none of my participants even know how to raise their hand!).

Then my cohost says that an ad*lt video is showing on everyone's screen, from the visitor. My cohost could not remove the visitor , and because the names in the participant list kept moving around (I'm guessing because of the hand-raising they were somehow doing).

So.  My guess is the visitor had an ad*lt video as their background and then did a spotlight for all, which overrode the screen sharing I was doing.

AND... SOMEHOW they were able to raise other participants' hands.  HOW ON EARTH ARE THEY ABLE TO DO THAT?!?

I ended-up killing the meeting to stop it.

Thanks for any thoughts on what happened!