party horn; party blower
A paper or plastic toy that unrolls and makes a sound when blown into; also called ピロピロ.
See also: ピロピロ
We blew party horns at the birthday party.
Compound of 吹き (fuki, 'blowing') + 戻し (modoshi, 'returning'), from the way the rolled paper returns to its original shape after being blown.