off one's high horse
see on one's high horse.
What’s The #’s Real Name?A hash has referred to stripes on military jackets since as early as 1910. But, in the 1980s, people started using hash to refer to the # symbol.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.