coup de main - noun
kü-də-ˈmaⁿ
Definition of coup de main : an attack that achieves complete surprise.

Watch Charli XCX & Haim perform 'Warm' together live.

Haim joined Charli XCX on-stage during her show at The Wiltern in Los Angeles this week to perform their collaboration 'Warm' together live.

Watch fan-filmed videos of the performance below...