hands up!

Từ điển Oxford Advanced Learner 8th

ˌhands ˈup! idiom
(informal)
1. used to tell a group of people to raise one hand in the air if they know the answer to a question, etc.
•Hands up all those who want to go swimming.
2. used by sb who is threatening people with a gun to tell them to raise both hands in the air
Main entry: ↑hand_idiom