Need help finding animation

It's a video of an alternate ending to the genocide fight with sans that is the most accurate to sans's character I'd ever seen. It's nothing flashy really, just instead of getting slashed after he falls asleep at the end, he actually manages to keep up and dodge a couple dozen more slashes in a row. After that, he decides "fuck it" and pulls out his most devious and laziest solution yet. He writes his name on a rock, amd tells you he's just gonna leave and that the rock is your opponent. Can't kill it, because it was never alive to begin with, so you're actually just stuck now.

I've been trying to find it for weeks, both on reddit and youtube, and came up empty