I don't think this has been mentioned before.
1. Make a new world (flat)
2. build straight up with dirt as high as you can, and place a single "clone-TNT" block on the very top. (By clone TNT I mean select the "block that explodes into a 5x5x5 pile of blocks" and then select TNT as the type of block it explodes into)
3. Drop down to the ground, then dig straight down directly below the dirt tower you just made (actually you can be one block over and it will still glitch)
4. When you get to the bottom place one block of normal TNT.
5. Light the TNT on fire. It will explode over and over again, forever (until you save and exit).
What the chirp is happening here? Somehow the "clone" block at the top is getting ignited by the TNT at the bottom. I think it's cloneing TNT into the empty space below the bedrock (which you can't see). This TNT explodes, which activates the clone-TNT again and the process repeats. But when the top clones into the bottom, the top doesn't catch fire or get destroyed because it thinks the fire/explosion is happening at the bottom. Or something.