Question

Hot under the Collar very angry; upset

Accepted Answer

Better say good night. My father is starting to get hot under the collar. Though this expression became popular in the 1800s, it has been observed for centuries that when people become angry, their faces and necks tend to turn red. And under their collars, their necks are getting hot. You'd better watch out! They might blow their stacks.

Idiom	Hot under the Collar
Example	Better say good night. My father is starting to get hot under the collar.
Meaning	very angry; upset
Origin	Though this expression became popular in the 1800s, it has been observed for centuries that when people become angry, their faces and necks tend to turn red. And under their collars, their necks are getting hot. You'd better watch out! They might blow their stacks.

Hot Collar Necks Good Night Father Starting Angry