a loose cannon

a person who cannot be completely trusted because their behaviour is sometimes strange or violent He's seen as a loose cannon by other team members. If anyone's going to get into a fight, it'll be Pete.

Common Names:

Name	Pronounced	Usage
Petronia	-	Ancient Roman
Zalman	-	Yiddish
Davida	-	English (Rare)
Leoncio	le-ON-thyo (Spanish), le-ON-syo (Latin American Spanish)	Spanish
Thomson	['tɔmsn]
Lorainne	lə-RAYN	English (Rare)