in a bad mood; sulky or irritable (used to describe someone who is displeased).
彼は今、機嫌の悪い顔をしているから話しかけないほうがいい。
He looks in a bad mood right now, so it's better not to talk to him.
朝から機嫌の悪い店員に注文を取られて気分が悪くなった。
I felt bad after being served by a grumpy clerk since the morning.
機嫌の悪いときは冗談を言わないでください。
Please don't tell jokes when they're in a bad mood.
昨夜よく眠れず、今日は一日中機嫌の悪いままだった。
I didn't sleep well last night, and I stayed in a bad mood all day today.