What does "须发皆张" mean? 须发皆张


须 - Beard

发 - Hair

皆 - All

张 - Spread/Open up

If it was directly translated, it would be something like "[someone's] beard and hair all spread open", but what does that even mean?

I can't really imagine how the person would look, so would the person have hair and a beard that stood up, like how someone would after their hair was affected by static electricity?
言未訖，只見關公口開目動，鬚髮皆張，操驚倒

Before he had finished speaking, he looked at Lord Guan and saw: 
His mouth was open, his eyes were starting,
His beard and hair were all bristling and crackling!

Cao Cao was petrified with fear.