I'm certainly seeing some Monty Python influences here. We've all wondered the same thing as the character here. "What the hell? Falling rocks? Seriously?" But you've taken it a step further and showed us how the poor rock feels about all this. It's a unique idea and gave me a decent laugh.
The sound effects were well done, as well as the voice acting. I've nothing more to say about that. You did a good job.
Animation wasn't very strong. I'd like to make a few suggestions on that.
First I suggest a longer pause between when he asks, "What does that even mean" and when he gets hit. That will allow all the other stuff that I'm about to suggest.
When the rock hits the character, I'd suggest making a "squish" animation. It doesn't have to be much. Just a couple of frames that shows the rock squishing him. After that, he might be lying under the rock, broken. Or maybe just an arm sticking out. Or maybe just a growing pool of blood. There's a lot that you can do.
Also, the centre of origin for the dust is where the rock first hit the guy. Rather, it SHOULD originate from where the rock hits the ground, and it should be flowing off to either side of the rock. Drop a stone in the dirt a couple of times and watch how it all behaves.
I'd also like to see more movement of the character. Maybe have him look up with a terrified expression just before the rock hits him. One other suggestion is maybe a shadow over the character that grows until he gets hit.
All in all, a good work. I'd love to see this made into a series. I feel like you could go a long ways with it. It's pretty funny and full of potential.