to proclaim the absurditiy of a situations circumstance or express disdain for some idiot's unintentionally comical and ignorant statement. Usually used after an interjection of somesort.
After Eric missed the easy layup with the greatest of magnitude, Kevin threw his arms in the air and yelled, "oh miggity!".
Eric's statement about being good at Halo recieved a big "oh miggity" from the group.