I mean, the definition is based on an example: supporters of the USSR's use of tanks to crush the Hungarian Revolution of 1956.

But other examples include denying or excusing authoritarian behavior carried out by nominally "socialist" regimes: imprisoning or executing dissidents, imperialism, suppression of freedom of expression, etc. Usually there's an undertone of double-standard where regimes that call themselves "Communist" or "Socialist" are excused for actions which would be considered authoritarian oppression under a liberal government.