Always fun/beautiful: a gorilla doing a chest beat!
First how they do it. Not like 99% of the humans do it, with the fists. Itīs also not with entirely flat hands, they made a sort of a half īcupī with their hands and then beat their chest (or legs, or bely, or buttocks, or head or wherever on their body *wink*). Doing it with their fist like humans do would be stupid. First of all it hurts and second it doesn't make the sound 'a half cup' does.
Like I said: always fun/beautiful. First of all I just love the sound of it. I have a chest beat from a wild silverback as WhatsApp notify sound. Second, it looks great. Especially when a silverback does it. But I don't see that happen often. Wild gorillas mostly do it to chase other nearby males away.
That's another thing: all gorillas do it! I often hear "look, he's practising", but that's incorrect. It's not that a young gorilla doing it is always a boy who's practising for when he's a silverback. Gorillas do a chest beat when they're: angry, upset and scared, when they want to be tough, when they want to show off, when they want to impress, but mostly when they want another gorilla to play with them. Especially young gorillas do it, but I also saw (young) adults females do it.
Here a chest beat (7 photos behind each other) from Shomari a few years ago.