got up on the wrong side of bed

To be in a particularly and persistently irritable, unhappy, or grouchy mood or state, especially when it is out of keeping with one's normal disposition. I'm sorry I snapped at you earlier, I think I just got up on the wrong side of the bed today. Geez, the boss has been in a really bad mood all day. I guess he must have gotten up on the wrong side of bed!

Fig. to seem grouchy on a particular day. Did you get out of the wrong side of bed this morning? You are a real grouch.

Be in a grouchy, irritable state, as in What's got into Max today? Did he get up on the wrong side of bed? This expression alludes to the ancient superstition that it was bad luck to put one's left foot down first, and was so used in a number of 17th-century plays. By the early 1800s it was associated more with ill humor than misfortune.

In a moody, grumpy state of mind. This expression dates from ancient times, when it was believed to be extremely bad luck to put the left foot down first. Supposedly Augustus Caesar, the Roman emperor, was exceedingly superstitious about this practice. It was still regarded as a bad omen in the seventeenth century, when the expression appeared in several plays (William Congreve’s Love for Love; Ben Jonson’s Tale of a Tub; Aphra Behn’s Town-Fop: “Sure I rose the wrong way today. I have such damned ill luck”). By the nineteenth century, however, it specifically became a sign of churlishness and ill temper. “Thou art angry this morning . . . hath risen from thy wrong side, I think,” wrote Sir Walter Scott (Redgauntlet, 1824).