three-alarm fire
1. A fire that is so large or intense that it requires the presence of many firefighting units to try to contain it. A three-alarm fire is the reason we heard all of those sirens last night
2. Someone or something that is very intense or stressful. Boy, this project has really become a three-alarm fire with all the other problems it's created.
a three-alarm fire
and a five-alarm fire n. someone or something very exciting. Work was a nightmare today. A five-alarm fire with crisis after crisis.