A lot of talk about "professionals doing their job" here.
Well, I'm sure it depends on the airline, but I have witnessed some pretty unprofessional behaviour by cabin crew on board an aircraft.
If you want to prevent these kinds of situations arising, deal with them when they arise in a professional, assertive manner.
That means: NOT pissing with laughter while you make a PA, NOT flirting with other members of the cabin crew and NOT muttering rude comments about the people on the flight deck which are clearly audible to the first row of passengers.
And don't be surprised when perfectly rational people get a little unsettled at seeing what they think is smoke in the cabin.
Finally, to flight deck and cabin crew, if you actually made your pre-flight PAs audible and spoke clearly, maybe more passengers would listen!