expression, ichidan verb
blow a bubble (with bubble gum)
Describes the action of inflating bubble gum into a balloon-like bubble. The verb 膨らませる is the transitive form of 膨らむ.
子供が風船ガムを膨らませて遊んでいる。
The child is playing by blowing a bubble with bubble gum.
風船ガムを膨らませるのが得意だ。
I'm good at blowing bubbles with bubble gum.