This is the word you use when there are no words that have the definition you need. It can basically mean anything, but commonly means something positive, like fun.
Much like the word Nigga for African Americans, "Jun" is a slang term for Asian Indians and comes from the word Injun. Is commonly used by Indians, but there is no remorse in letting White people or other races using it as long as they are your friends.
This is NOT pronounced like the Asian name Jun (Pronounced "June" or "Joon",) but rather is pronounced "juhn" like how you would say the end of the word Injun.
Another variation of this word is inja.
"Yo, whaddup jun?"
"Jun, you crazy"
"We gonna jump that fuckin jun"
"I'm a jun, son"
"Thanks man, you my jun"