Derived from shout at to get shirty although completely different in meaning.
"I'm not getting shouty."
"She was getting shouty with him"
"James got shouty several times last night."
"I do like to get shouty sometimes."
In less respectable areas of the UK it may be used like so;
"She was getting WELL shouty"
"He was getting ALL shouty"
however most people using the phrase like this have been shot at by Cal as this is a gross act of disrespect to the founders of this articulate expression of anger.