Edinburgh (Scotland) slang for Heart of Midlothian Football Club, or "Hearts" for short. The nickname Jambos comes from the rhyming slang Hearts - Jam tarts. A bit silly, but there you go.
The singular, Jambo
, is often used offensively by supporters of rival Edinburgh team Hibernian, or "Hibs" or "Hibees
" (pronounced Hybees).
Like many cities, the rivalry between local football clubs can be intense, and although some might say it's "just in jest", the language used to describe supporters of the rival team can be offensive.
So: Hearts fans sometimes describe Hibs fans (Hibees) in derogatory terms, and Hibs supporters do likewise with Hearts fans.
As an unbiased observer. and looking through the posts in this dictionary from people who have written "definitions" which are nothing more than insults, and don't even explain what they're talking about; there are more insults written by "Hibees" about "Jambos" than there are vice versa. Furthermore, Some of the "Hibees" have written "definitions" of themselves which are self ingratiating and self congratulatory. On balance it looks to me like it is the "Hibees" who lose at the diplomacy game!
Btw The Urban Dictionary guidelines/rules state that inside jokes will be rejected, so that, and the fact that these posts contain no actual definition, should be enough to have them removed from the dictionary. On the other hand, they represent a record which tells a story!