happy slapping

 Longman Dictionary of Contemporary English 5++朗文当代英语 5++LDOCE 5++朗文 5++ˌhappy ˈslapping noun [countable, uncountable]  the act of deliberately attacking someone and filming the attack on a mobile phone 开心掌掴，巴巴乐〔指故意掴人耳光并用手机拍下攻击过程〕

ˌhappy ˈslapping nounChineseSyllable  

happy slapping
ˌhappy ˈslapping noun [uncountable and countable]
the act of deliberately attacking someone and filming the attack on a mobile phone

happy slappingBrE /ˌhæpi ˈslæpɪŋ/ 🔊NAmE /ˌhæpi ˈslæpɪŋ/ 🔊 noun (BrE) [uncountable] the practice of several people attacking sb while another person in the group makes a film of the attack 开心掌掴（指几人围殴一人，由同伙将袭击画面拍下）