It's not the story that revolves around a top hat keeping you hostage. It's not the puzzle-platforming that has you navigating grid-based levels and dangerous blocks. It's not even the fart jokes. The reason Battleblock Theater will always have a place in my heart is down to three simple words: "it's a secret."
When I played Battleblock Theater, I decided to leap from block-to-block with my housemate. Why go it alone when gem-collecting with a pal is so much more fun? Plus, in co-op, you're able to use your buddy's head as a platform. Extra blocks!
We were having a nice time, flinging one another across gaps. Nothing major. Then we happened upon our first secret area and narrator Will Stamper went from exaggerated talkyman to Scatman John on hallucinogenics. It was like Richard Pryor had come back from the dead to deliver a knockout set just for the two of us, as we couldn't contain our laughter while "IT'S A SECRET" bellowed from the speakers.
I dunno, maybe you had to be there. The only thing I'm certain of is that we were pretty sure that we were witnessing the height of comedy at that very moment. Sometimes it's the silly things you can't explain, eh? Makes sense if it's a secret, I s'pose.