If something or someone is Not cool, ugly, dumb, slow, retarded, not hip, old-fashioned.(Depends on if you put neg. emphasis on the word)
Billy had on the 1932 air force ones in the year 2008. Susy came up and said, "Billy your shoes are so jheezy, don't ever wear them out in public again."
If something or someone is: good, cool, hip, fab, fly, dope, fresh, klean, pretty, sweet, nice (Depends on if you add positive emphasis)
Susy walked in the door with the latest-flyest nike kicks on her feet, Billy looked at her and said, "WOW, your kicks are mad jeezy susy!"