There are various synonyms for "out of humor" that can be used to describe someone who is in a bad mood or feeling grumpy. Some of these synonyms include "irritable," "cantankerous," "sullen," "moody," "cranky," "surly," "testy," "ill-tempered," "gruff," "peevish," "grumpy," "snappy," and "cross." Each of these words conveys a slightly different nuance of being in a bad mood or feeling out of sorts. By selecting the right synonym, you can more accurately capture the intended meaning and tone of your message.