When a person is considered to be in bad shape, the phrase generally means that he either is in poor health or not physically fit. Some residents in North America and Europe use this idiom to describe a person who is in the hospital under a serious ailment, possibly even close to death. In lighter circumstances, a doctor may also say that his patient is in bad shape when a test result reveals something negative that could lead to poor health. The term bad shape can also be used literally, meaning that a person needs to start eating better and exercising to lose unwanted weight. Other situations the phrase bad shape could be used would be to describe a pregnant female, a person with financial difficulties, or someone who is intoxicated.
Most of the time, when someone mentions the term "bad shape" in North America, he or she is referring to someone who is in poor physical condition. Likewise, a doctor may use the term "good shape" to describe someone who has passed a physical or received excellent test results, but it could just as easily be applied to dozens of other positive scenarios. The term is used so generically that a passerby who heard someone use the phrase would have no idea what was being referred to, even if he knew the people speaking.
Although the literal definition would seem to point to someone who is in bad physical or mental shape, it can also be used to describe a number of other scenarios as well. If someone's car stalled on the freeway, for example, and he had to walk to a repair station only to learn that his wallet was still in the vehicle, the service attendant may use the phrase to describe the situation. Another use of the phrase is when someone has consumed so much alcohol that he can barely stand; his friends may laugh and use the expression.
The phrase "bad shape" is one of many English sayings that are classified as idiomatic expressions. Usually, the meaning of idioms is a phrase that would make no sense to anyone outside a group or culture that uses the word because the literal definition would mean something else entirely. For example, another American idiom is a "high five," which means to slap hands above each person's heads in greeting or celebration. Other cultures might not understand the term.