finger whistle; whistling with fingers
Refers to the act of whistling by placing fingers in the mouth, or the sound produced. A common technique for producing a loud, piercing whistle.
He whistled with his fingers to stop a taxi.
指笛のやり方を教えてください。
Please teach me how to do a finger whistle.
Compound of 指 (yubi, 'finger') and 笛 (fue, 'whistle, flute'). The reading ふえ becomes ぶえ due to rendaku.