Oh Michael Jordan. According to my wife and kids; Michael says it because he doesn't like using the lords name in vain, so instead, the next best thing.
Guy: I just swished from half, backwards.
Girl:OMJ! Oh My..ckle Jordan, awesome!
*highfives*
OMJ - Acronym for "Oh My Jonas!", used by fans of the Jonas Brothers. Taken from the internet term OMG. Note how "Jonas" has replaced "God" - the Jonas Brothers are a pop/rock icon that millions of girls everywhere worship.
text version of the phrase 'Oh My Jon'. Used within the Fueled by Ramen fanbase as an exlamation to anything shocking or exciting. Was named after Jon Walker, bass player for the bandPanic at the Disco.