After transforming into a Legendary Super Saiyan, Broly powers up to such a degree that his screams and laughter cause an earthquake as well as a thunderstorm to appear.
Broly utilizes this technique successfully the next day shortly after Super SaiyanVegeta's Photon Bomber failed to kill or even injure him. The power-up is enough to create an earthquake that causes some damage to the winding path between Paragus' spaceship and castle. Thunder comes down while Super Saiyan Broly enters a state of hysteria and transforms into a Legendary Super Saiyan.
He later used this to transform into a Legendary Super Saiyan again when confronting Gohan on Earth seven years later, as the latter had transformed into a Super Saiyan 2.
In Dragon Ball Super, Kale uses a slightly different variant when assuming her berserker state.
It is implied that Broly was attempting to use this technique to turn into the Legendary Super Saiyan during his fight with Goku late at night, although it was prematurely interrupted when his father Paragus barely managed to reassert control over him via his crown.