Mecha flex on 'em.
B.R.U.T.A.L. Dab dance is a Common Fortnite Emote.
This emote was added at Fortnite Battle Royale on 1 August 2019 (Chapter 1 Season 10 Patch 10.0).
The gesture B.R.U.T.A.L. Dab belongs to Chapter 1 Season 10. It's not yet known how to get the gesture B.R.U.T.A.L. Dab.