"Join the club" is an American idiom which means that other people, particularly the person using the idiom, can relate to the issue or situation that the person he or she is speaking to is in. In essence, it means that the speaker is not alone but is, in fact, in the same position as others. English sayings like "join the club" are not meant to be taken literally, but are figurative forms of expression instead.
Similar idiomatic expressions include "welcome to the club," "welcome to my life," or "been there, done that." Just as the phrase "join the club" does, these expressions portray a familiarity with a particular issue or set of circumstances. The meanings of idioms like these are not always immediately understood by non-native English speakers or people with cognitive disabilities and may even be interpreted literally, but most Americans automatically understand these expressions without need of clarification.
It is not uncommon to hear a person say "join the club" to another person who is expressing difficulty or a particular hardship. This expression is most often used in relation to negative events or circumstances. For instance, a parent may complain to a friend about a child's poor behavior at a certain age and the other parent, to show that she or he identifies with the speaker, may say “join the club” as an indication that similar parenting issues are currently being experienced.
In addition to "join the club" being a popular American idiom, the similar expression of "welcome to the club" is used by Australians in much the same way. Just like its American usage, this phrase is an informal expression that may lead to two or more people bonding over a sharing of thoughts and feelings about certain events. While this idiomatic expression is not referring to an actual club or actively recruiting new members to a club, people who use the expression sometimes do form actual clubs and support groups after discovering that others can identify with or are faced with similar circumstances.
No record of this phrase's original use exists, but "join the club" has been used as an expression for several generations. It is unlikely that many Americans or Australians have wondered about the origins of the expression since it is so commonly used in casual conversation. Unless speaking to a non-native English speaker who is unfamiliar with the term, "join the club" usually does not require research concerning its definition.