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

Watch: Lana Del Rey and Jack Antonoff perform 'Margaret' live.

Lana Del Rey popped up as a special guest during Bleachers' set at High Water Music Festival in Charleston this past weekend, performing 'Margaret' live with Jack Antonoff for the very first time.

Watch clips of the performance below...