waking up on the wrong side of the bed

To wake up on the wrong side of the bed means to be very grumpy, moody, or irritable in the morning as well as someone who will be easily annoyed by other people and things. This is usually a phrase said to someone in the early hours who seems to be in a very bad mood since they woke up, to which someone will humorously say to them they must have woken up on the wrong side of the bed that morning.