Definition of rent-a-crowd in English:

rent-a-crowd

(also rent-a-mob)

noun

British
informal
  • A group of people regarded as regularly or instantly available for an expedient purpose, especially a public demonstration.

    ‘this was no rent-a-crowd chanting demands or brandishing placards’
    ‘he brought a rent-a-crowd of supporters with him’
    ‘the people who protested were just a rent-a-mob’