Like violent moshing, slang

• Belligerent, in British slang
• Bother filling bag (groan)
• Violence in the past involving King George
• (informal British usage) aggravation or aggression
• Old King, in past, threatening action
• Violence in an attempt to capture king
• Pugnacity of a gang going round Oxford, originally
• About to blow, in slang
• Intimidating behaviour in the past involving historic monarch

Longman Dictionary of Contemporary English Word definitions in Longman Dictionary of Contemporary English
noun EXAMPLES FROM CORPUS ▪ A different set of rules then operate to impose limitations on the expression of aggro . ▪ If there was aggro she could handle it. ▪ This could cause aggro with Dev's girlfriend Geena. ▪ When she returned there would be aggro ...