set off

verb

1. To leave; to begin a journey or trip.“He set off in search of better opportunities.”
2. To begin; to cause; to initiate.“I had no idea that one simple comment would set off such a huge argument.”
3. To cause to explode, let off.“What a tragedy, that someone would set off a bomb in a crowded place.”
4. To make angry.“Don't set him off or he won't shut up all day.”