someone's blood is up
US /ˈsʌm.wʌnz blʌd ɪz ʌp/
UK /ˈsʌm.wʌnz blʌd ɪz ʌp/

1.
激怒している, 興奮している
someone is very angry or excited
:
•
When he heard the news, his blood was up and he started shouting.
その知らせを聞いて、彼は激怒し、叫び始めた。
•
Don't say anything to him now, his blood is really up.
今彼に何も言うな、彼は本当に怒っている。