expression, noun
shriek of delight; cry of joy
Used when someone is so happy or overwhelmed with positive things (e.g., busy with enjoyable work, receiving too many gifts) that they let out a playful 'scream' of joy or mock distress.
注文が殺到して、うれしい悲鳴を上げている。
We're swamped with orders and letting out shrieks of delight.
旅行の計画が楽しすぎて、うれしい悲鳴が出そうだ。
Planning the trip is so much fun I could let out a cry of joy.
Compound of 嬉しい (happy) and 悲鳴 (scream, shriek). The phrase figuratively describes a joyful 'scream' arising from an excess of happiness or pleasant busyness.