A large pebble the size of a small pebble

A little larger than a golf ball.

Something that produces a loud exclamation in a movie character, but possible permanent brain damage IRL.

Yea, what creeped me out, is this must have been done before, and got whatever effect the bird intended. hard to say what it’s motives were of course but they’re smart enough to know what they are doing

Where I am from, a rock is by definition huge. It sounds like the bird dropped a stone.

If the stone the crow dropped weighed a stone, that's a big fuckin' rock where I come from.