on one's high horse meaning

1. In an attitude of fancied superiority
2. Very much on one's dignity

[American slang]
Fig. in a haughty manner or mood.
  Larry is on his high horse again, bossing people around.
  The boss is on her high horse about the cost of office supplies.

• off one's high horse:    [American slang]ad ...
• come down off one's high horse:    [American slang]v. ...
• get (down) off one's high horse:    [American slang]Fi ...