It's the next big event in Fortnite. From April 24 to 26, Travis Scott in collaboration with Epic Games will offer you a show in the battle royale, unveiling a brand new song and exclusive in-game cosmetics. Some of them will be accessible via challenges, and Bounce on several giant Astro heads is one of them.
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Giant Astro heads are inflatable Travi Scott balloons, similar to those on the cover of his "Astroworld" album. They can be found near the concert stage, north of Sweaty Sands.
Get materials, make a ramp to reach the top of the heads and bounce back to complete the challenge. Once done, you'll get the Astro Antidote Spray. By completing all three challenges, you'll get the Rage Emote.