Every bed has two sides: the wrong side and the right side. The pleasantness of your daily experience depends entirely on making sure you get out of the right side of the bed. If you don't, you will have a terrible day, and people will invariably ask in an annoying voice: 'Who got out of the wrong side of the bed this morning, then, eh?'
Getting out on the right side can be trickier than it sounds because it is often not possible to determine beforehand which side of the bed is the right side and which is not. To make matters worse, recent advances in mathematics have concluded that there are many more dimensions floating about than we had previously thought, making it very much more likely that the side you do eventually choose will be the wrong one.
With this in mind, it is often best to simply stay in bed until the right side becomes obvious.