This is the 6346th most frequent Russian word.
флешмоба
A "flash mob" – a group activity where people gather suddenly in a public place to perform and disperse quickly.
The word 'флешмоб' is used here as a noun to describe a lively and organized public performance event.
На площади прошёл увлекательный флешмоб с участием танцоров.
An exciting flash mob involving dancers took place in the square.
The word 'флешмоба' is employed in the singular genitive form to indicate the event being organized.
Организация флешмоба требовала чёткой координации.
Organizing the flash mob required precise coordination.
Here, 'флешмобу' appears in the singular dative case, indicating the act of joining the event.