on one's soapbox

on (one's) soapbox

Vocalizing one's opinions, beliefs, or ideologies in an impassioned, impromptu manner, often to others' annoyance. (Soapboxes were once commonly used as makeshift platforms for such speeches.) Once grandpa got on his soapbox about the local election again, I found an excuse to slip out of the room. Whenever Jim is on his soapbox like this, I just try to tune him out.
See also: on, soapbox

on one's soapbox

Expressing one's views passionately or self-importantly, as in Dexter can't resist getting on his soapbox about school expenditures. This expression comes from the literal use of a soapbox as an improvised platform for a speaker, usually outdoors. [Mid-1600s]
See also: on, soapbox