The bathroom is a magical place where many different things can happen. The original use is obviously to take a bath (look at the word, dumbass), and to take a crap or pee. But many other things can happen in the bathroom nowadays, such as listening to music, throwing a party, studying, reading, eating (yep, that's right, eating), going on your laptop, your iPod, your iPhone, or even hanging out with your friends. The bathroom is the room where the most things can happen, and therefore is the greatest room.
"Hey, what's you're favorite room in your house?"
"THE BATHROOM, OF COURSE"