and everyone thinks tabs are bad…
Yep. Perfectly legal notation, literally impossible to play. Epic troll by Brahms.
(Also on a side note, even excluding the impossible notes, I think the guy is underselling the difficulty of playing polyrhythms like that - that’s pretty advanced piano. I never got near that level anyway )
The best troll I’ve ever heard of is Mozart’s piece “Cosi Fan Tutte” which he wrote for an opera singer he disliked… he knew that she had a habit of dropping her chin for low notes and throwing her head back for high notes so he wrote the piece to make her look like she was bobbing her head like a chicken