Keep your phones and gadgets in Do Not Disturb mode.
Avoid discussion on topic which can offend others. This includes but not limited to politics, sex and religion.
For the Speaker
Prepare well for the meetup - an event is attended by 50-100 people who give their
time for your talk. And the worst which can be given to them is sloppy talks.
For the Audience
Questions are usually encouraged at the end of the talk. This does not interrupt
the talks flow.
Connection with other fellow open-source enthusiasts and contributors, share what you are building/working on and how you are doing it
and receive feedback on the same.