Went to a foreign country for vacation and bought a whole-ass bale of hay. Most of the dream was me trying to smuggle it home through customs.

The town was infested with some sort of radioactivity from underground that was hurting people. I had to crawl underground, through these super-tight tunnels deep under the earth with things getting more and more evil as I went, until I was able to track the source of the radioactivity to a giant monster that lived back up on the surface (via the tunnels) in an abandoned barn. I had to fight the monster, but I could fly inside the barn. I ripped its head off, but every time I did, it was just like a big rubbery mask and a new head grew back, until I figured out how to do it fast enough that it wouldn’t have time to pop a new head out. When I did that, the real head came out: Tux the Linux Penguin.

That broke the immersion enough that I woke up, all amped up from adrenaline from fighting the monster.