An onomatopoeic adverb describing something gushing or pouring out all at once with force.
コップを倒してコーヒーがドバッと床にこぼれた。
I knocked over the cup and the coffee gushed out onto the floor.
駅に着くと人がドバッと改札口に押し寄せた。
When the train arrived, people surged all at once toward the ticket gates.
袋を破ると、中身がドバッと出てきて驚いた。
When I tore the bag, the contents spilled out all at once and I was surprised.