For most airliners, it is allowed for crew to take 'companion' passengers, like friends or family on a flight. The companion must still pay for the ticket, but

For most airliners, it is allowed for crew to take 'companion' passengers, like friends or family on a flight. The companion must still pay for the ticket, but it is usually sold with a hefty discount. Companions also have no guarantee of a seat, if the flight is overbooked, you're out of luck. But.... on most flights it is allowed to have more passengers than seats, this all has to do with regulations on cabin-crew members vs number of passengers. So, it is not unusual for companions to sit in the cabin or cockpit jumpseat, or, you guessed it, the crew rest. As long as the regulations allow this of course. I have flown many times as a companion, mostly in smaller planes (that do not have a crew restroom), but also a couple of times in a 747, which have crew rests in the cockpit (2 full-size bunkbeds, and 2 business class seats and a bathroom).