This one takes the form of a darkly humorous limerick by Robert Conquest, who, in addition to be one of Communism’s earliest and fiercest critics, was also something of a poet:

There was an old Marxist called Lenin
Who did two or three million men in.
That’s a lot to have done in,
But where he did one in,
That Grand Marxist Stalin did ten in.

H/T: Niall Kilmartin at Samizdata