Binding of Isaac has an achievement for "A Gift From Krampus". The hint says it's in Satan's room, but I don't know where that is.
How to get A Gift from Krampus
achievementsthe-binding-of-isaac
Related Solutions
To say that the Binding of Isaac supports the use of a gamepad would be a slight exaggeration.
The latest patch for the game added control options to the game, which looks like this:
And as you can see, the game specifically tells you to use one of the many gamepad to keyboard solutions out there, specifically JoyToKey. This thread describes the alternative of using ControlMK, with specific instructions and even a ready-made setup profile for the game (though I can't vouch for its quality as I have never tried it). The thread also mentions Xpadder, as per Kalamane's answer.
I personally use the DS3 tool and a Dualshock 3 (I actually prefer the keyboard, but my keyboard has some key-locking issues so I can't walk diagonally and shoot right at the same time).
According to comments on the wiki, "Everything is Terrible" makes alternate colored monsters and bosses more common. This is actually good, because alternate colored monsters tend to leave drops on kill.
According to the mechanics guide, it also makes Curses more common in Wrath of the Lamb.
Additionally, however, bosses drop one less heart pickup (heart, half-heart, spirit heart) than they previously did.
Best Answer
Amongst other factors, beating the boss without losing health increases your chance of seeing satan's room, occasionally satan will not be there and you can instead fight Krampus. He fights similar to the fallen.