JOAM (also written with some or all letters lowercase) is the abbreviation "Joke Of A Man". Joam is considered to be an insult, and thus, it is a popular abbreviation among American teenagers. The word was believed to have originated at LaSalle University, and it has become a common word primarily in the North Philadelphia area. Words that are generally associated with JOAM include "clown", "jokester", and "joker".
As stated above, JOAM is mostly used as an insult, the severity of which is determined by the context in which it is spoken.
For example, someone might describe someone that tells tall tales and engages in ridiculous activities as a "complete Joam". In sentence form, it might be used like, "That guy is a complete JOAM". JOAM can also be used as an adjective to describe something (such as a location or item) if it is to be of 'JOAM status'. For example, the Home Depot might be rebranded as the "JOAM Depot".