could you please help to decipher the meaning of the idiom "I could just spit"? I have a sentence: "I'm so sick of people I could just spit", but I've also found many examples in google, such as "I'm so excited I could spit" or " I'm so tired, I'm practically furious. I could just spit " Only one source, also in google :) gives the meaning "of being very angry", but how being very angry is compatible with excitement?
Suppose that doesn't mean spiting in a direct sense, does it?
Thank you very much!