Two robots enter, both robots stay, only one has a slightly elevated head. Minecraft craftsman Sethbling has recreated the 1964 sensation that swept an easily-amused nation, Rock'em Sock'em Robots.
The classic two-player big robot battles comes to life in Mojang's pile of virtual building blocks, using a rather ingenious little pressure plate mechanic to simulate the pulse-pounding battles of the original game. It's red versus blue in its earliest form, the moveable though somewhat janky object versus the other moveable though somewhat janky object.
Back when I was a little kid Rock'em Sock'em Robots would amuse us for whole minutes at a time, after which we'd start breaking bits off and throwing them at each other. I suppose you could do the same thing with the Minecraft version. Download it yourself via the link in the YouTube description and find out!
Rock 'Em Sock 'Em Robots in Minecraft [YouTube]