Grimein' it out

When you dance aka skank to grime music.
In more detail: You pull your arms up to come level with your chin and pull backwards while fists are clenched in a in circle motion next to your ears.

Ellie: Emma I'm putting our song on.
Emma: Which one?
Ellie: Migraine skank!
Emma: GRIMEIN' IT OUT!
Ellie: Yeah boys.