Derived from the commonly used term OMG or OMFG. Has the same meaning as the above, the only difference is the G is spelled out gangsta-style and has more emphasis in order to really get your meaning of 'Woah!' or 'I just can't believe that' across. Can be used to express both good and bad emotions, depends on the situation.
Boy: You are so fine I would enjoy a date with you.
Girl: OMFGOTZ ARE YOU SERIOUS YAH!!!