Every flight I have been on where the crew have been kind enough to let me occupy the jumpseat, I have been given a thorough safety briefing as soon as I enter the cockpit.
One occasion earlier this year on a jumbo springs to mind where the resting pilot told me "that in the event that we need to get out quick we can leave either by the pilots window or by the hatch in the roof. You will go first followed closely behind by my boot!"
Dingbat.