Most NFL referees do in fact have other jobs, ranging from dairy farmer to teacher to attorney to entrepreneur/inventor. The NFL is the only major sports league in the US that does not hire referees on a full time basis and, contrary to what most people seem to believe, the pay is not amazing ($25.000-$70/000/year. Baseball refs start at $120k and top out at $300k+, plus per diem on road trip plus benefits. Basketball refs range from $100-300k plus benefits. NHL refs make $72-255k).
Most NFL referees have other jobs and work those during the off season. Some NFL referees are business owners or attorneys.
they trian for there next game
Cash bribe checks and stare at the sun for hours at a time
NHL Referees make $127,000 a season
NFL referees were never volunteers. However, many of them got their start in recreational leagues near their hometowns as volunteers.
They earn between $25k and $70k per NFL season. Since they are considered to be part-time employees, this isn't too bad. As a reference: NBA/MLB referees will earn from $100k to $300k per season, thanks to their much fuller schedule.
They are assigned to each game
The referees in an NFL game have a very difficult job in calling the game they are assigned to. The highest paid among the referees is unknown.
The League pays the salaries of the referees who work games in the NFL. The NFL Officials Union and the NFL agreed to an 8 year contract in 2012. The deal, the longest ever between the league and union, was brokered after the Refs went on strike and refused to work games in the 2012 season.
In the NFL, "flag" is usually used as slang for the yellow penalty markers which are thrown by the umpires, referees and side judges.
Referees don't play in the game, silly.