on 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

Speaking one's views passionately or self-importantly.
See also: on, soapbox