get on one’s high horse—(also: ride one’s high horse) become dignified and formal; assume an arrogant mien:
- As soon as I said a little slang to her she got on her high horse.
get on one’s horse—(sl.) hurry; start at once:
- You better get on your horse if you’re going to make that plane.
Note: The expression does not correlate in meaning with the phrase be on the horse—(Drug users) be under the effects of or addicted to heroin:
- How long have you been on the horse?