A year or two ago, LEGO's DC Superheroes line released a set called "Dynamic Duo Funhouse Escape." At the time, I thought it was pretty awesome -- It had minifigs for Batman, Robin, the Joker and Harley Quinn, an appropriately creepy setup for a villainous hideout, and even a little roller coaster car that traveled through it on tracks. It was neat. And then Brickbaron came along and basically made it look like baby school with his version of the Joker's funhouse, complete with carnival rides, deathtraps and puzzles, all of which are motorized to put the whole thing in motion.
It's quite possibly the coolest LEGO build I've ever seen. Check it out in full video, complete with sound effects for Batman's eternal spin-kick, below!