Bother with a horse, say, otherwise go back

• ___ Crag (climbing challenge on Nickelodeon's "Guts")
• Hostile behaviour
• In fighting mode, slangily
• Big trouble
• About to blow, in slang
• (informal British usage) aggravation or aggression
• Violent behavior, in British slang
• Trouble as a horse runs over

Wikipedia Word definitions in Wikipedia
Aggro is a slang term meaning aggravation or aggression . "Aggro" may also refer to:

Wiktionary Word definitions in Wiktionary
1 (context Australia NZ slang English) angry. 2 (context online gaming MMORPG slang English) Liable to attack without being attacked first (said of monsters). 3 (context British US slang English) hardcore, aggressive. n. 1 aggravation; bother. 2 (context ...