Hungarian Communist parties (there were two of them, the Hungarian Working People’s Party/Magyar Dolgozók Pártja, MDP was reorganized after the 1956 revolution as the Hungarian Socialist Worker’s Party /Magyar Szocialista Munkáspárt, MSZMP) gave regular financial support to Western socialist/communist parties.
This was done for a number of reasons. These included:
spreading the word, helping the communist cause
helping to spread pro-Soviet/communist propaganda
influencing left-wing politics in the West
providing cover for intelligence/spying activities
Although the practice was widely known, the particulars were only uncovered in the early 1990’s when researchers were given access to certain Hungarian and Soviet archives.
The ensuing political scandal was named “rolling dollars”.
Since then the term became synonymous with illicit political financing but in the other direction. Parties are regularly claimed to be financed by shady foreign actors. Most of the time the mysterious foreigners are suspected to be George Soros or other liberal Jewish people or organizations.