on one's high horse
1．being very proud and scornful 趾高气扬；自高自大
I don't like him：he's always on his high horse， thinking he can order
everyone else about．不喜欢他，他总是趾高气扬的，以为什么人都得听他的。
Martha was chairman of the picnic committee， and at the picnic she was on her high horse， telling everyone what to do．玛莎是野餐会的主席，在野餐时她盛气凌人地指挥每个人怎么做。
2． in a bad temper发脾气．The girl was on her high horse because she found her boyfriend insincere．姑娘发现她的男友不诚实，非常生气。