单词happy-slapping
n.: 开心掌掴（指几人围殴一人，由同伙将袭击画面拍下）网络: 乐掴；掴掌乐；掌掴乐
开心掌掴（指几人围殴一人，由同伙将袭击画面拍下）:
the practice of several people attacking sb while another person in the group makes a film of the attack