happy slapping

noun

1. informal.
   the practice of attacking, esp slapping, an unsuspecting passer-by and filming it with a mobile camera phone, footage of which is then circulated for the amusement of others

Word History and Origins

Origin of happy slapping¹

C21

Example Sentences

But the spokesman adds that the rash of "happy slapping" incidents a couple of years ago forced local authorities to confront the issue, and gradually a consensus is emerging.

From The Guardian

The judge said: "By recording parts of what you did on a mobile, you made at least some of this an example of happy slapping."

From BBC

He rose confident and happy, slapping his friend on the shoulder, with the old boyish exhilaration.

From Project Gutenberg