ringleader - Someone who is the main influence or motivator behind a particular action or event, especially a disruptive or controversial one.

The police managed to arrest the ringleader of the gang, who had coordinated the series of robberies across the city.
hiccup - An involuntary spasm of the diaphragm, resulting in a sudden, brief sound caused by a quick intake of air, often followed by a noticeable "hic" sound.

A girl in the class couldn't stop her hiccups, and the other kids in the class couldn't stop laughing.