The term 'dog-tired' or 'cat burglar' is an IDIOM which means to be exhausted or to be a thief who specializes in stealing from people's homes. It is believed to have originated in the early 20th century, when burglars would climb through windows and other openings to gain access to a home. The phrase is used to describe someone who is so tired that they are unable to do anything else, or someone who is a skilled thief.